By then we were in very bad shape. The kapok life jacket becomes waterlogged. It’s good for about 48 hours. We sunk lower down in the water and you had to think about keeping your face out of water. I knew we didn’t have very long to go. The men were semicomatose. We were all on the verge of dying when suddenly this plane flew over. I’m here today because someone on that plane had a sore neck. He went to fix the aerial and got a stiff neck and lay down in the blister underneath. While he was rubbing his neck he saw us.

As soon as the Trinity nuclear test had been successfully concluded on the 16th July the USS Indianapolis had been despatched from Mare island, San Francisco to Tinian island in the mid Pacific. The heavy cruiser carried the Uranium that would arm the Little Boy bomb.

By 29th July she was en route back to the Philippines across the remotest reaches of the ocean. Her captain had discretion not to zig-zag and it may have made no difference that she was not.

A new study of the sinking published in 2018 reconstructs the events aboard the Japanese submarine I-58, captained by Hashimoto

I-58’s crew waited, breathless. The black shape on the horizon soon gathered itself into the shape of a triangle suspended in the moon’s silver light. But looking through the night periscope, Hashimoto still could not determine her class. Neither could he see the height of her mast in order to estimate the range. This lack of data opened the door to an array of possible mistakes, and his mind ticked through them all. Without the range, course, and speed of the target, he could not make the proper calculations to obtain a hit. If the class of ship were known, he could estimate the speed by counting the target’s propeller blade frequency, but the hydrophones remained silent. And with the target pointed directly at him, its hull was masking sonar sounds. He would have to wait until the target was on a broader line of sight to ferret out its speed. Also, changes in the target’s speed and course could throw off Hashimoto’s aim, especially at night, so the moment of firing had to be determined in advance. A whole kingdom of errors loomed. But if Hashimoto could keep them small and fire six torpedoes in a fanwise spread, he could ensure a hit. Even if he guessed wrong on one of the variables – or even if the target zigzagged, as it was almost sure to do. A crisp demand interrupted his calculations: “Send us!” It was the suicide pilots. Hashimoto had been so preoccupied with his Type 95 torpedo calculations that he had not followed up on his earlier order for the kaiten. “Why can’t we be launched?” the pilots clamored. Hashimoto understood their desire. The kaiten could steer to the target, regardless of its speed or course. But the touch-and-go, obscured visibility would make it difficult for the pilots to home in visually on the target over a period of tens of minutes. To get a Type 95 torpedo hit, all he needed was a reasonable estimate of speed and range, along with one good bearing, and he could send his fish to their target. That was the better option here, so he decided not to use the kaiten unless the oxygen torpedoes failed to hit their mark. Hashimoto put his eye to the scope again and saw the top of the triangle resolve into two distinct shapes. He could make out a large mast forward and estimated its height at ninety feet. His heartbeat quickened. She appeared to be a large cruiser, ten thousand tons or bigger. Now I-58’s hydrophones gurgled to life, announcing enemy propeller revolutions that were moderately high. Using visual observations, Hashimoto adjusted and put the target’s speed at twelve knots, course 260, range three thousand yards. He alone could see all this. Without him, the crew could know nothing. As they awaited his word, straining in the deadly quiet, an exhilarating thought formed in his mind: We’ve got her. … Aboard I-58, a sonarman thought he heard the clinking of dishes.‘ Twenty-seven minutes had passed since I—58’s navigator spotted the enemy ship. It now became apparent that the target was approaching off the starboard bow. He ordered the torpedo director computer set to “green sixty degrees”——the torpedoes would turn sixty degrees starboard after launch. The target closed the distance: twenty-five hundred yards… two thousand… fifteen hundred. “Stand by…” Hashimoto commanded in a loud voice. “Fire!” At two-second intervals, six torpedoes ejected from tubes carved into the sub’s forward hull, one tube after another until all six were away. A report came from the torpedo room: “All tubes fired and correct.” It was about five minutes after midnight, and six warheads streaked toward the enemy warship in a lethal fan. Hashimoto snatched a look through the periscope, brought his boat on a course parallel to the target, and waited. Every minute seemed an age.

The Indianapolis was steaming straight ahead when she was hit by three Type 95 torpedoes from the Japanese submarine I-58 at 23:35. Some U.S accounts put the time at 00:14.

Contrary to US Navy claims during the war and after, the Indianapolis was not observing radio silence because of the secrecy of her mission – she managed to transmit distress signals which were received by three separate US Navy monitoring stations, a matter that has only emerged from later de-classified documents. None of the three stations acted on the information. At 00:27 on 30 July, Indianapolis capsized and sank carrying around 300 men with her. The remainder of her 1,196 crew went into the water, only a limited number of lifeboats had been deployed and a minority of the men had life jackets.

Approximately 900 men now faced a hellish ordeal as they struggled to survive in the warm seas, with little or no water. They faced severe sun burn, dehydration, hypothermia – and sharks. Some have argued that the incident amounts to the largest single shark attack in human history. An account by the surviving Chief Medical Officer on board, Dr Lewis Haynes throws some light on the extent of the shark hazard:

I slowly walked down the side of the ship. Another kid came and said he didn’t have a jacket. I had an extra jacket and he put it on. We both jumped into the water which was covered with fuel oil. I wasn’t alone in the water. The hull was covered with people climbing down. I didn’t want to get sucked down with the ship so I kicked my feet to get away. And then the ship rose up high. I thought it was going to come down and crush me. The ship kept leaning out away from me, the aft end rising up and leaning over as it stood up on its nose. The ship was still going forward at probably 3 or 4 knots. When it finally sank, it was over a hundred yards from me. Most of the survivors were strung out anywhere from half a mile to a mile behind the ship. Suddenly the ship was gone and it was very quiet. It had only been 12 minutes since the torpedoes hit. We started to gather together. Being in the water wasn’t an unpleasant experience except that the black fuel oil got in your nose and eyes. We all looked the same, black oil all over – white eyes and red mouths. You couldn’t tell the doctor from the boat seamen. Soon everyone had swallowed fuel oil and gotten sick. Then everyone began vomiting. At that time, I could have hidden but somebody yelled, ‘Is the doctor there?’ And I made myself known. From that point on – and that’s probably why I’m here today — I was kept so busy I had to keep going. But without any equipment, from that point on I became a coroner. A lot of men were without life jackets. The kapok life jacket is designed with a space in the back. Those who had life jackets that were injured, you could put your arm through that space and pull them up on your hip and keep them out of the water. And the men were very good about doing this. Further more, those with jackets supported men without jackets. They held on the back of them, put their arms through there and held on floating in tandem. When daylight came we began to get ourselves organized into a group and the leaders began to come out. When first light came we had between three and four hundred men in our group. I would guess that probably seven or eight hundred men made it out of the ship. I began to find the wounded and dead. The only way I could tell they were dead was to put my finger in their eye. If their pupils were dilated and they didn’t blink I assumed they were dead. We would then laboriously take off their life jacket and give it to men who didn’t have jackets. In the beginning I took off their dogtags, said The Lord’s Prayer, and let them go. Eventually, I got such an armful of dogtags I couldn’t hold them any longer. Even today, when I try to say The Lord’s Prayer or hear it, I simply lose it. …The second night, which was Monday night, we had all the men put their arms through the life jacket of the man in front of him and we made a big mass so we could stay together. We kept the wounded and those who were sickest in the center of the pack and that was my territory. Some of the men could doze off and sleep for a few minutes. The next day we found a life ring. I could put one very sick man across it to support him. There was nothing I could do but give advice, bury the dead, save the life jackets, and try to keep the men from drinking the salt water when we drifted out of the fuel oil. When the hot sun came out and we were in this crystal clear water, you were so thirsty you couldn’t believe it wasn’t good enough to drink. I had a hard time convincing the men that they shouldn’t drink. The real young ones – you take away their hope, you take away their water and food – they would drink salt water and then would go fast. I can remember striking men who were drinking water to try and stop them. They would get diarrhea, then get more dehydrated, then become very maniacal. In the beginning, we tried to hold them and support them while they were thrashing around. And then we found we were losing a good man to get rid of one who had been bad and drank. As terrible as it may sound, towards the end when they did this, we shoved them away from the pack because we had to. The water in that part of the Pacific was warm and good for swimming. But body temperature is over 98 and when you immerse someone up to their chin in that water for a couple of days, you’re going to chill him down. So at night we would tie everyone close together to stay warm. But they still had severe chills which led to fever and delirium. On Tuesday night some guy began yelling, ‘There’s a Jap here and he’s trying to kill me.’ And then everybody started to fight. They were totally out of their minds. A lot of men were killed that night. A lot of men drowned. Overnight everybody untied themselves and got scattered in all directions. But you couldn’t blame the men. It was mass hysteria. You became wary of everyone. Till daylight came, you weren’t sure. When we got back together the next day there were a hell of a lot fewer. I saw only one shark. I remember reaching out trying to grab hold of him. I thought maybe it would be food. However, when night came, things would bump against you in the dark or brush against your leg and you would wonder what it was. But honestly, in the entire 110 hours I was in the water I did not see a man attacked by a shark. However, the destroyers that picked up the bodies afterwards found a large number of those bodies. In the report I read 56 bodies were mutilated, Maybe the sharks were satisfied with the dead; they didn’t have to bite the living.

Their ordeal had been lengthened because the failure of the Indianapolis to arrive in the Philippines when expected was also not reported, and no search for the ship was ever undertaken. Instead they were spotted by chance at 10:25 on 2 August by a PV-1 Ventura on a routine patrol. They still had to spend the rest of the day in the water before help arrived:

It was Thursday [2 Aug] when the plane spotted us. By then we were in very bad shape. The kapok life jacket becomes waterlogged. It’s good for about 48 hours. We sunk lower down in the water and you had to think about keeping your face out of water. I knew we didn’t have very long to go. The men were semicomatose. We were all on the verge of dying when suddenly this plane flew over. I’m here today because someone on that plane had a sore neck. He went to fix the aerial and got a stiff neck and lay down in the blister underneath. While he was rubbing his neck he saw us. The plane dropped life jackets with canisters of water but the canisters ruptured. Then a PBY [seaplane] showed up and dropped rubber life rafts. We put the sickest people aboard and the others hung around the side. I found a flask of water with a 1-ounce cup. I doled out the water, passing the cup down hand to hand. Not one man cheated and I know how thirsty they were. Towards the end of the day, just before dark, I found a kit for making fresh water out of salt water. I tried to read the instructions, but couldn’t make sense of it or get it to work right. My product tasted like salt water and I didn’t want to take a chance so I threw it into the ocean. I then went to

pieces. I watched the PBY circle and suddenly make an open-sea landing. This took an awful lot of guts. It hit, went back up in the air and splashed down again. I thought he’d crashed but he came taxiing back. I found out later he was taxiing around picking up the singles. If he hadn’t done this, I don’t think we would have survived. He stayed on the water during the night and turned his searchlight up into the sky so the Cecil J. Doyle (DE-368) could find us. The ship came right over and began picking us up.

See Lewis L. Haynes, “Survivor of the Indianapolis.” Navy Medicine 86, no.4 (Jul.-Aug. 1995)