Answer: caissons

AnswerCrossword Clue
CAISSONSWatertight structures
CAISSONSAmmunition chests
CAISSONSTwo-wheeled artillery wagons
CAISSONSThey went rolling along in old US Field Artillery song lyrics
CAISSONSChests for holding ammunition.
CAISSONSChests for ammunition
CAISSONSCarriages used at presidential funerals
caissonsA chest or wagon for holding or conveying ammunition
caissonsA large watertight chamber, open at the bottom from which the water is kept out by air pressure and in which construction work may be carried out under water
caissonsCAISSON, a watertight chamber
caissonsA floating vessel or watertight structure used as a gate across the entrance of a dry dock or basin