In February 2009, 24-year-old Nick Schuyler went fishing with three friends in the Gulf of Mexico. An attempt to salvage a stuck anchor capsized the boat, and the four men were forced to cling to the hull to survive. When rescuers found the upturned boat after 43 hours (see picture, above), he was the only one still alive.

It was going to be our last fishing trip. I knew Marquis [Cooper] and Corey [Smith] from the gym – I was their personal trainer and we'd become good friends – but the following week Marquis was moving away. We'd been fishing once before and I didn't enjoy it that much – the anchor of Marquis's boat got stuck and we'd had to cut it free. But we decided to go out one last time. One of Marquis's friends couldn't make the trip, so at the last minute I invited my best friend, Will [Bleakley], from my college football team.

Photograph: AP

On the morning of 28 February, we motored three hours out to sea. We knew there was a cold front coming in, and the sea was rough, but we weren't planning to stay out that long. I got sick on the way out though, and I was really cold, even in my winter ski jacket, so at about 4pm we decided to pull up anchor and head home early.

The anchor was stuck again. 'We're not going to lose another anchor,' we said to ourselves. So we decided to floor the engine and see what happened – the line would either snap or become loose. In fact, the line got really tight, and then the back of the boat shot down and the boat flipped over. The four of us were thrown in.

The water was so cold, we were in complete shock. Our first thought was to try to flip the boat back over. We were as strong as oxes, but in rough seas and with no leverage, it was never going to happen. So we hung on to whatever we could at the back of the boat and waited to be rescued.

Corey had a waterproof watch, and we knew Marquis's wife would call the coastguard if the boat wasn't back by a certain time. We thought they'd rescue us by 2am at the latest.

The seas got worse, you couldn't see where the waves were coming from. Then it got darker and colder; you couldn't see your hand in front of your face. We didn't know it at the time, but the rescue helicopters had been delayed by the bad weather. When we finally saw them, after about 10 hours, they flew straight over our heads. They were looking for a little white boat upon thousands and thousands of whitecaps.

By that time, Marquis was deteriorating. He wasn't wearing much clothing and his body was so cold. We didn't know the symptoms of hypothermia, but his eyes were at the back of his head, he was slurring and foaming at the mouth. Eventually he lost consciousness. Then Corey developed the same symptoms. The hypothermia made him aggressive and he started pulling on Marquis.

I struggled to hold on to Marquis for about an hour, but he died in my arms, and eventually we had to let him go – otherwise, we were going to lose Corey at the same time. That was by far the hardest thing I've ever had to do.

It wasn't long before Corey started to struggle. I was holding on to his jacket, but he kept trying to jump off the boat. Eventually he got away from me. We were yelling at him, but one of the side-effects of hypothermia is that you think you're hot and take off your clothes. He took off his life jacket and just swan-dived into the sea.

Will and I were alone. We tried to keep each other going. The sun was coming up and we told each other we were bound to get rescued, but the weather kept getting worse and the waves higher. The helicopters and planes couldn't see us. We spent the whole day fighting to hold on to each other and the boat. Will was a strong swimmer, and he was able to dive under the boat to get supplies – sports drinks and pretzels – but when he got back he wouldn't eat. He was developing the same symptoms as Corey and Marquis. He didn't get aggressive, just very weak, and I knew it was just a matter of time. I felt helpless.

To watch these three athletes, my friends, go out that way, it was the hardest thing. But I knew I wasn't going to quit. I tried to keep the image of my mother in my mind – I thought about her attending my funeral. I knew I wanted to live to tell people what had happened. After a few hours on my own, I started hallucinating and caught myself yelling. My heart rate got really slow and it was hard to breathe. I knew I was dying. I thought about cutting myself, trying to write something on my arm. I just wanted to tell the story.

I didn't even see the rescue boat until it was right beside me, and then I couldn't believe it was real. I had been on my own for 18 hours; in the sea for 43 hours in total.

I've thought a lot about why I survived. I was in the best shape of my life, and I was wearing my winter jacket, so I was better insulated. But a lot of it was luck: it could have been any one of those guys. And to be saved, to see my family again – it was the most bittersweet feeling imaginable. I knew there were three families who were still hoping their sons would be found.

The worst was having to tell them what had happened. But still the search carried on, and I had to sit there in hospital, knowing they wouldn't find anyone alive.

I lost roughly 40lbs [18kg], tore my groin and my hip, and the ends of my big toes might always be numb, but that's not a big deal. I've had survivor's guilt, particularly at first. And there were lots of rumours afterwards – about us giving up, about inexperienced boating. So I wrote a book, Not Without Hope – not only to honour my friends but to get closure, for myself and for the families. They've dealt with the grief in their own ways, but I'm the only one who knows the truth.

It would be different if I'd been able to save somebody. But to come out of that water on my own, knowing I'd lost three friends – it's very hard.

Photograph: Reuters

Bahia Bakari was the sole survivor of Yemenia Airways flight 626, which crashed into the Indian Ocean near the north coast of Grande Comore, in the Comoros islands, on 30 June 2009. A schoolgirl from the outskirts of Paris, now 14, she was on her way to the Comoros for her summer holidays with her mother, Aziza Aboudou, who was among the 152 passengers and crew killed. She spent nine hours in the water, clinging to a piece of wreckage.

Suddenly, the lights started flickering, and the passengers became more and more anxious and panicked. The hostesses told us not to worry, that this happened sometimes because of bad weather; it was nothing. Mummy seemed calm, confident, she was smiling at me. She ran her hand through my hair. I turned my head to the window and pressed my face really hard against it, trying to see what was happening outside. A sudden loud whistle ran through the cabin. My head was like in a vice. There was a deafening noise of crumpling metal. I felt myself sucked out by a superhuman force. There were several explosions. I felt a big shudder, like an electric shock, run through my body. It anaesthetised me. Then I didn't feel anything, no pain. I plunged into a black hole.

I tried to open my eyes. How much time had passed? How long had I been unconscious? I was in water, underwater. My lungs were blocked up. I couldn't breathe. My body drifted up to the surface, I got my head out. I breathed in, at last. My lungs were burning, I was coughing and spitting; my throat was on fire. My left eye hurt terribly. I was alone in the middle of the sea. My clothes were heavy, my shoes weighed a tonne. I moved my hands and legs to keep my head above water; my shoulder hurt, and my hip. It was a black night, no moon, but I saw four pieces of white debris not far away from me. I managed to swim to one, and tried to climb up on to it. I couldn't stay sat on it; it was smaller and less stable than I thought. And I couldn't pull my legs up; they hurt too much.

The waves were huge; three times as tall as my dad. I was exhausted, I just wanted to sleep. So I rested my head on the debris. I thought about my mother. I thought she must have arrived at the airport by now and be wondering where I was. She must be really angry with me, that I'd managed to fall out of the plane into the sea just before we landed – I hadn't listened to her, again. I should have done my seat belt up tighter, and not looked out of the window, not leaned over so far. And she must be worried to death about me.

I closed my eyes. When I woke up, it was dawn. The sea was more and more agitated. I was terribly thirsty, and I couldn't feel my legs. But I was still clinging on to my piece of debris. I saw land, not too far away, green and yellow. I shouted for joy and tried to paddle towards it, but I realised it was actually getting farther away. I lost sight of the land.

It wasn't until the boat had found me and I was in the hospital in Moroni the following day, 1 July – after my uncle Joseph had been in to see me – that a psychologist came. She was a white lady. She told me I was the only survivor of the plane crash, that I was lucky to have escaped, but that one day, perhaps in 10 years, I would feel guilty to have lived. I didn't understand her. I had fallen from the plane, I knew that. But why was she talking to me about a crash?

Then I had an awful premonition. 'Why isn't mummy here with us?' I asked. She said: 'You know, I don't think they found your mother. They only found you.'

The coldness of those words, the offhandedness, almost destroyed me. In the sea, on my piece of debris, I had really believed I was the only one to fall out of the plane. Mummy couldn't have disappeared; mums don't disappear. The woman carried on talking, but I wasn't listening. And yet, little by little, I began to understand: I wasn't the only one to have fallen from the plane – everyone, passengers, captain, crew, they all fell. Mummy, too.

Even so, it wasn't until much, much later, back in France, with Daddy and my brothers and sisters, that I understood I would never see her again.

Marcus Luttrell

In June 2005, US Navy Seal Marcus Luttrell took part in Operation Red Wing in Afghanistan, to capture or kill Taliban leader Ahmad Shah. When three goat herders discovered their hiding place, the men voted to let them go. Shortly after, they were ambushed. Nineteen men were killed in the resulting gun battle – Luttrell was the only survivor. Wounded, he hid in a nearby village for six days before being rescued.

We were on a ridge watching the target when they came up behind us and started firing. I don't know why I survived. I'd put my foot one way, and step. And someone else would do the same thing and get hit. That's one of the things about being a lone survivor – you don't know why.

My skill level wasn't superior to anyone else's. I wasn't in any better shape than anyone else. We were all hit multiple times. I just outlasted it. So many guys were hit so many different times, they just bled out.

I watched all my guys die, but somehow I managed to crawl to safety. I escaped to the mountains. I must have been on my own for a day and a half – it's a blur really. I was dehydrated and bleeding to death. Eventually I was found by some local villagers. They took me in. At the time I didn't know why, but I discovered it's a tradition in that village. They take in travellers, people who are injured, and give them food, shelter and do everything they can to keep them alive – that includes defending them against enemies. I had gunshot wounds, broken bones, lacerations from the trees and rocks, but they took care of me until I was eventually rescued on 4 July.

I've never questioned why I survived, but I'm doing everything I can to repay the people who helped me in my recovery. I started the Lone Survivor foundation, and I work with a campaign called When They Come Back We Give Back, which helps veterans returning from conflict situations.

I remember the guys I lost every day – I play the scenario in my head every time. But I'm alive, and I don't take that for granted.

Photograph: Courtesy George Burk

Captain George Burk was the sole survivor of a military plane crash in 1970. The 13 other crew members were killed. He had 65% burns and spent 18 months in hospital. He has dedicated his life since to motivating others.

It was like sticking a needle in a balloon. Shortly into the flight, the window glazing cracked, there was a boom and the plane decompressed. We pitched nose down, the windows blew out. The noise was deafening. Papers, clothing, everything was being sucked out of the windows.

There were 14 of us on board. Our crew chief was trying to hold the door on and my boss was flying the aircraft, but the left side of the cockpit was split open. Next to him was Daryl Robinson, or Robbie. His head was off his shoulders.

I sat back down, buckled my seat belt and assumed the survival position. My life didn't flash in front of me, but the last thought I remember having was, 'I hope my insurance policies are intact.' My children were six, four and two. I knew I was going to die, but the mind has this numbing mechanism. I was aware of everything, but I felt it wasn't really happening.

I remember the impact. The bending, breaking and shearing of metal. I was thrown violently back against the seat, then forward, breaking my nose on the seat in front. I had no sensation of blood, though; my adrenaline was pumping.

The next sensation was as though someone had dumped a large bucket of scalding hot water on me. Everything went black. I opened my eyes. I was face down outside the plane, my hands were charred and black, and the skin on my left hand was hanging off. I remember looking at my feet and finding it rather unique that my right shoelace was tied and my left one was gone.

I looked around me. I could see our crew chief, he was badly burned and dead. Near me was another body – Bob Ward, I knew him quite well. I remember thinking, if I sit here I'm going to die. I felt a terrible pain in my back, but I managed to walk. I was just praying to God to not let me die in this field alone, without a chance to say goodbye to my family. All the things that I thought were important – about my career and whether or not people liked me – was nothing; it didn't mean anything.

I started to go into shock and lay down under a tree. I knew I was dying. I felt like I was being stung by millions of bees. The bad cop in my head told me to close my eyes and go to sleep, the good cop was saying, if you close your eyes, you're going to die. I don't want to die. Focus, focus, focus. I held pictures of my children, their mother, my parents in my head. I could have closed my eyes so easily.

I heard voices coming towards me. I forced myself to my feet, waving my arms, then fell back down in a heap. A firefighter leaned over me. I heard his voice crack as he said, 'Oh my God.'

When I got to hospital, my total body surface was 65% burned, with a little more than 50% third-degree burns; the fingers on my left hand had burned down to the bone. I have no recollection of digging my way out of the plane through a crack in the fuselage, but apparently that's how I got out. I had a broken nose, a skull fracture, two fused bones in my neck, four cracked ribs, a fracture in my spine and my left shoulder is still separated. I was in hospital for months – it was a miracle I got out of intensive care.

Much later I found there had been problems with the pressure system on that aircraft before. It had been polished for inspection so often that perhaps the buffing had compromised the rivets.

There were no support groups in those days, and I didn't know about post-traumatic stress disorder or survivor's guilt. I didn't have anyone to talk to. Everyone on the flight and most of the guys I knew in the burns unit had died. I asked my doctor, 'What am I supposed to do with the rest of my life? Why me?' And he told me I had experienced the will to survive – he said I had to find my purpose.

It's been tough, and I still have my moments. I haven't been physically pain-free for 40 years, but it's the pain inside your head that will kill you; the guilt. I've tried to live my life in a way that honours the men who died, my family and the doctors and nurses who didn't give up on me or let me quit. I've realised that we're here for a reason – to make a difference – and that's what I've tried to do. To turn a negative into a positive.

• Bahia Bakari's story is extracted from Moi Bahia, la miraculee by Bahia Bakari and Omar Guendouz, published by Jean-Claude Gaweswitch. Edited and translated by Jon Henley.