To provide a movably installed underwater dome boat intended for use in underwater installation.

A surface junction passage part B is provided on a dome part A formed by a skeleton of structural material and a shell material 4 having a transparent window, and the dome part is provided with a buoyancy adjusting means 9, whereby the dome part is floated and sunk, and moved. In the case of sinking the underwater dome boat in a water area with a different depth of water, a vertical shaft 5 is provided with a vertically movable floating body deck 12, and mechanisms 15, 16a, 16b for positioning an opening part 16 communicating with an elevating means 7 above the water level, thereby preventing water from entering the interior of the vertical shaft part through the opening.