I heard a screwing noise as the hatch of our sub was sealed. A bright orange hose from topside that had been inserted into the sub to blow fresh air as we loaded had been removed, and the interior felt warm and damp and close. All was still.

Though I'd worried how I'd feel at this moment (like a mistakenly dead person might feel at hearing their coffin sealed?) what I felt was mostly excitement and anticipation. Laying on my stomach atop a towel and a big cushy pillow with my notebook and camera in hand, I didn't feel claustrophobic.The huge concave window in front of me showed a blue limitless ocean -- a whole world, previously forbidden, waiting to be explored. It was the opposite of confinement. It felt like freedom.

I'd only discovered the existence of the Curasub a few months previously, when I covered the work of scientist Carole Baldwin, a scientist from the Smithsonian who often uses the sub for her research and who has used the sub to discover more than 50 new species of fish in the "deep reef", an area of reef 500-1000 feet deep off-limits to conventional divers. I knew immediately it was something I had to do; as I wrote in my last post, visiting the deep sea has been a long-time dream of mine, and until I heard about the Curasub, I had started to give up hope I'd ever make it happen.

One of the mysteries I'd pondered before arriving in Curaçao was exactly who owned the sub. Pilot Barbara van Bebber cleared this up: it's owned by Adrian "Dutch" Schrier, a technical diver (and founder of the Curaçao Sea Aquarium) who purchased it as he got older and grew unable to do some of the deep dives he'd formerly done, but who also wanted to share the deep ocean with scientists and the public. Smithsonian scientists like Baldwin use the sub part of the time, and the rest of the time is available for tourists.

Earlier, the sub was hoisted from its berth and into the water of the dock. I replaced my shoes with black Substation Curaçao socks before I lowered myself in by bracing my feet on the window of the conning tower. The socks would keep my feet warm but also protect the submarine.

Inside the sub were four people: to my left, my husband; all the way in the back, Mark, a local dive shop owner; and in the middle of all of us in a fold-up plastic seat was Barbara, the pilot. Mark had windows of his own to his left and right and sat in a bench seat that could theoretically hold two, but only two people who feel your standard coach airline seat is spacious. He could also look out the front window past Barbara, but it was distant.

We'd already gone through a safety briefing on the sub, where the batteries were, what the parts of the sub were, and an overview of the different life support systems available should something fail. Everything on the sub has a backup, weights could be dropped in case of a need for emergency ascent (with no risk of decompression sickness since the cabin pressure would remain stable), and in addition, there was also 5 days food and water stowed inside.

Now Barbara asked for permission to submerge and it was granted, and the sub glided away from its mooring. The sandy bottom slipped by underneath us, and then the edge of the island shelf. Over we went.

We paused for some pictures at about 45 feet with a diver outside the sub who took our picture.

The warmth and humidity of the sub's interior made me glad I had worn shorts. I'd also brought pants and a jacket in case the sub was cold. I really had no idea how it would be. Barbara told us the stuffiness would abate as we descended into colder waters, and we'd only have to worry about getting cold were we on one of the scientific dives that last up to 8 hours. Knowing my bladder, that's not the only thing I'd have to worry about, but what the lady scientists do about that on long dives remains a mystery to me.

We dropped below 100 feet, the deepest I'd ever dived before. The island sloped steadily below us; the light steadily faded. At 191 feet we passed a thermocline, an internal boundary between two masses of water with different temperature. The water outside the window shimmered and blurred as the layers were roiled by our passing.

I was also surprised to feel the small tilts and turns of the sub as we moved in the water. They were gentle, but it was a sensation I hadn't expect and had never felt before. But my biggest surprise was how lunar our surroundings were.

I expected to see lots of life; but I saw lots of sand and rocks and a little life. I should not have been surprised. I've read about how most of the deep sea is relatively devoid of macroscopic life except in particular spots where food is abundant: seamounts, thermal and chemical vents, or places where the current brings or drops a lot of food. Yet somehow since the ocean documentaries focus on the organisms you do find (they do this for a very good reason: watching lots of sand, rocks and mud go by is boring), it had left me with the impression life was more common than it is.

I don't mean to say there is no life down there; there is plenty if you look. And of course, how much life there is varies by where you are in the ocean. Even on Curacao, just around the corner from the Substation, Barbara said, there was more to see. But other considerations dictated where the station could be put in and where its dives would take place.

Still, by comparison to the riot of life in a coral reef where I've done all my diving, the deep is austere.

On that rock you saw near the end of this video that Barbara said was among her favorite places corals perched and little fish hovered nearby, and in a crack stretching across its face were dozens of some sort of shrimp hanging vertically in the crevice and dancing back and forth. At the distance we hovered from them, they almost shimmered. Tried as I might to capture them on film, I could not. They were too delicate, and too far away.

At 274 feet we passed over another edge as the shelf we'd been following dropped again. On the rock wall rising in front of me were whip corals -- long wiry unbranched rods often curled into corkscrew squiggles at the tips -- and the occasional sea fan, a flat coral that radiates into a fan shape.

We saw a beer bottle. Mark recognized the brand, then remarked how he kept wanting to equalize as we descended and was surprised he didn't have to. I agreed. When scuba diving, you've got to grab your nose and blow to equalize your ears every 5-10 feet you descend so that the volume of air in your lungs and ear spaces can balance the pressure exerted by the water outside. To not be doing so was strange; so was not reaching down to check my pressure gauge every few minutes. That part of riding in a sub -- the effortlessness of it for the passengers -- was fabulous. "I tell people it's one of the easiest and safest activities you can do," Barbara said.

The tradeoff is the loss of intimacy. When scuba diving, you're part of the life. If you wish, you can get your face right up next to the tiniest blenny and gaze at it as long as your air and dive computer permit. Fish and other sea life react to your presence. Larval fish and jellyfish drift right by you. In the sub, you are separated by more distance from the life. The problem is compounded by the curvature of the window. The shape is necessary to protect us from the crushing pressure, but it also reduces the apparent size of everything by 1/3. So everything you see feels a bit remote, even when it's not.

At 452 feet we heard a disconcertingly loud pop of the sort heard in WWII sub movies when the boat goes deeper than it should to evade enemy depth charges. "That's the window seating," Barbara stated matter-of-factly.

As our lights picked out small fish, larger ones capitalized on our dive lights to spot and go after them -- several opportunistic red snappers employed this nasty trick to chase away the beautiful and newly discovered fish species we strained our eyes to see. At 478 feet, a red snapper chased a beautiful deep-sea yellow bass we were trying to admire under a rock, and at 504 feet, another snapper chased a longnose butterfly fish into a hole.

At 539 feet I saw something truly remarkable -- a coral or some other animal (predatory sponge?) of a type I'd never before seen. It looked like a dandelion with only a few huge seeds -- a creamy stalk supported a head with radiating extensions that themselves terminated in another radiation, just like dandelion seeds.

Here's a still image of a different one:

As you heard in the video, every 15 minutes we did a life support check prompted by a call from the surface. Barbara checked all her systems and had us check that the CO2 scrubbers were working by putting our hands in front of vents to the upper left of our couches. If we felt air blowing, they were.

We saw a jack-knifefish or hi hat -- an uncommon black and white fish with a resemblance to the Nike swoosh. Then we came across a few more signs of poor human habits -- an old tire, and a wad of tangled anchor rope. Although both were ugly, they did provide structure around which fish could gather and hide.

As we reached a place where the island turned a corner, suddenly there were many more sea fans, whip corals, and fish. The corner must be a place where the current is higher and more food is available.

We started to ascend. The whip corals multiplied into a garden around 180 feet, and the seafloor began to blossom back into the coral reef I'm familiar with from diving.

The warm, damp environment had faded into a very comfortable cool room temperature while we were deep, but as we grew shallower, the clamminess returned and the walls of the sub began to sweat.

Disconcertingly, we saw scores of invasive lionfish between 100 and 300 feet. These are depths which recreational divers that spear lionfish cannot reach.

Around 50-60 feet, we started to feel wave motion again.

As we pulled back into dock, I was happy with what I'd seen but already wanted more. Although I'd hoped to go to 800 feet, Barbara said the majority of things to see were around 500 feet and stopping there would maximize bottom time. It wasn't that there weren't unique lifeforms at a deeper depth -- it's just that the majority of a trip to 800+ feet at this particular location would be spent sand-and-rock gazing and not life-viewing (other parts of the island had more life at deeper depths, she said, but this is the part where the substation for many other practical reasons happened to be located). And since we were staying around 500 feet, we were not deep enough turn out the lights. I did ask.

Now I'm wondering about the Idabel over in Honduras, which I wrote about in my last post. It dives to up to 2000 feet. What might we see there, and will it be deep enough to turn out the lights and see the ocean light up? I'm not quite ready to take the plunge in Karl Stanley's hand-built sub yet. But just give me a few years. Curiosity will exceed timidity before too long.

Of course, deep-sea submarine diving is not only wonderment and safety checks, at least not when humans are involved. I will leave you with one of my favorite moments from the dive when someone in the back (Mark I think), points out a particularly peculiar sponge, visible here at the upper right of the rock. It's a little hard to hear him point it out, but it's easy to hear our reactions. Enjoy.