Workers lowered the video camera, thermometer, and dosimeter through the hole on the first floor of Reactor 1 building in the 2 to 10 millisieverts/hour environment.
Water is murky, 4.9-meter deep from the torus room floor. TEPCO said in the 2/20/2013 handout (in Japanese; there is no English handout) that visibility was about 60 centimeters.
From TEPCO's Photos and Videos 2/21/2013, with brief explanations of the photos from the Japanese version:
Suppression Chamber wall (OP 3200, in the water):
Torus room floor (OP -800):
Water surface (OP 3700):
Torus room ceiling (OP 7700):
(OP is "Onahama Peil", average sea level used for the plant. The numbers are in millimeters. So, OP 3700 means the level is 3700 millimeters (or 3.7 meters) above the sea level.)
It is stating the obvious, but it nonetheless did not occurred to me until I read the comment from the blog reader Atomfritz - that the Reactor 1's Suppression Chamber is also broken.
TEPCO's video shows (from 35 to 45 seconds in the video) a large pile of sediments on the torus room floor under water: