Abstract: Floating apparatus for performing operations, such as dredging and drilling, on and in a bottom under water subject to violent motion. The apparatus comprises a working platform provided with legs vertically adjustable to the depth of the bottom by adjusting means. Each leg is flexibly connected at least at two vertically spaced places to parts of the apparatus formed integrally with the platform. The connection of a leg at the higher of the two places is effected by means for taking up rocking movements of the working platform, and at the lower of the two places by connecting members springing and/or dampening in two perpendicular horizontal directions, while the means adjustable in the vertical direction for connecting the leg to the working platform are also of resilient or dampening construction.