caisson

A (permanent) enclosure from which water can be expelled, in order to give access to underwater areas for engineering works etc.

A structure with similar function that is temporary.

A coffer (sunken panel).

The gate across the entrance to a drydock.

A floating tank that can be submerged, attached to an underwater object and then pumped out to lift the object by buoyancy.

A two-wheeled, horse-drawn military vehicle used to carry ammunition (and a coffin at funerals).

A large box to hold ammunition.

A chest filled with explosive materials, used like a mine.