A: The "bubble" is a 5 1/4" thick acrylic sphere. It is about 6 feet (1.8 meters) in diameter and weighs about 5000 lbs. Two people can go down in the sphere at the front of the sub and two people can go down in the chamber behind the sphere. (We refer to this second chamber as the "stern" in the logs since it is located closer to the stern or back of the sub than the front compartment.)
Usually there is a sub crew member and a research crew member in each compartment. As a scientists sees something of interest, he or she informs the sub pilot where he/she would like to go. The sub pilot essentially drives the sub around the ocean with directions from the scientist. A backup pilot sits in the stern chamber just in case something should happen to the pilot. If something did happen, the backup pilot can bring the sub up to the surface.
The main purpose of going down in a sub is to get a visual of what it looks like on the deep ocean floor. Another goal is to collect specimens for identification while gathering as much information we can. The sub can collect specimens through a vacuum tube that pulls the sample through a hose and deposits it in a bucket attached to the sub. A mechanical arm can collect things like coral and sea stars.
(Follow this Harbor Branch Oceanographic Institution link to see a video of the sub collecting several different samples. Just choose your preferred format from the selections 3/4ths of the way down the page.)
During the dive, there are as many as three video cameras rolling
and a few still cameras to capture research images and information.
The video footage and still images are helpful in identifying
what we see as well as documenting the world below for the public