The Bathysphere is always kept in a small room at the lower level of the ComVee. Whenever the ComVee is floating on a body of water, the Bathysphere could be launched out the bottom of the ComVee to be used for underwater expeditions. In its appearance, Angelica Pickles jumps into and steals it, and uses it to go find and pick up the babies and Nigel Thornberry. After diving down in it, she activates it's flare and accidentally hits the ComVee with it causing it's pontoon to pop and causes the ComVee to sink to the bottom of the lagoon. Eliza then discovers Angelica in the bathysphere as she disappears into a waterfall as she drives it underwater to find the babies.
After Angelica finds and picks up Tommy, Chuckie, Phil, and Lil, Kimi, Dil, Susie and Nigel Thornberry in a cave, she and Susie then have an argument while Angelica tried to drive the bathysphere which caused it to go out of control and crash to the bottom of the sea. Debbie and the rest of the Thornberrys and the babies' family were though able to find the Bathysphere and save them before they could run out of oxygen.