Abstract: The disclosure relates to an enclosure for installation in the seabed comprising an elongate container for holding a payload. The container has a plurality of passages extending lengthwise of the container and an impeller at the lower end of the container for drawing water through at least one or said passages to form a slurry with the material of the seabed and for discharging the slurry at the upper end of the container into the surrounding water. The enclosure has inner and outer concentric passageways extending lengthwise thereof and said impeller has a blade or blades extending across the inner and outer passageways. The blade of the impeller has a first portion pitched to draw water down one of the passageways to the lower end of the container and a second portion pitched to discharge slurry up the other of the passageways to the top of the container.

Abstract: The disclosure relates to an enclosure for weaponry, listening, identifying, recording, communications equipment or the like for use in or on the seabed. The enclosure comprises an outer cylindrical container (10) having a buoyancy chamber (34) to render one end (11) of the container more buoyant than the other (12) so that the container lies in a vertical orientation when disposed in the sea. At the other end (12) of the container there are propeller/impellors (28) for activating sand/silt/shingle on the seabed to create a cavity below the container into which the container can self bury. A container has a payload compartment (32) for holding weaponry, listening, recording and/communications equipment.