This is a tool-assisted speedrun. For more information, see http://tasvideos.org/2599M.html
Entirely unrelated to the TV series seaQuest DSV, Seaquest is a submarine combat game in which you control a water vessel and must pick up divers at different levels of depth while avoiding fish and enemy subs. While most of the game takes place underwater, you also must resurface for air from time to time so your air meter doesn't run out.
Like Tetris (http://tasvideos.org/1596M.html) , the game