As part of our trip on the Argos in Cocos Island, we signed up for 2 dives on the onboard sub from DeepSee submarine that is part of the boat (although sub dives do cost extra :) ).
The sub is a 3 person sub (pilot and 2 passengers), has 3 different battery systems, and the equivalent of a rebreather system for the cabin to give occupants breathable air for 3 days in case of emergency. While it has full freedom of movement, it's not very fast for horizontal trust, so it gets towed by the surface boat which also keeps constant comms (both voice and telemetry). The cool thing is that they can send location to the sub underneath by locating it compared to the boat's GPS location using sonar.
After arriving Cocos on the Argos and doing some dives on the first day, the second morning we went for our first dive to 100 meters. The whole thing was almost 2H.
A few pictures below:
A few short clips from my camera:
And a 6mn summary of the whole thing taken from my gopro (feel free to skip forward inside it, it's not action packed :) ):
The next afternoon, we went back for a longer 3H+ dive to 300 meters. We got lucky to see Rays swimming around us during the dive, and had a peek at the ocean bottom and the critters that live there in virtually no light:
Here are some videos of the rays going around us during the dive:
And 7mn summary of the 3h dive:
So, my impressions?
It's obviously an experience in a lifetime, not many people have gone to 300 meters under water
As a geek, of course, I could not but be impressed with the sub. It's super cool see it work, especially if you think about the geolocation technology, marine com technology, and how it can even know how it's moving compared to the ground thanks to 4 sonar pings going down and using the doppler effect on the returning signal.
Taking pictures was difficult because the dome acts as a big prism that splits light colors and makes all pictures somewhat blurry, especially if you try to zoom. The one exception are pictures you're taking without external lighting (mostly pictures above you) which since they're mostly blue, don't have the light splitting problem and look nicer.