SeaSoar is a a towed, undulating measurement package. The
moveable wings are contolled by a topside computer which sends
up-down signals via the conducting tow cable. The wings are moved
by a ... hydraulic unit which is powered by an impeller on the tail
of SeaSoar. Data is returned to a topside computer network via
the conducting cable.
Additional info and pictures at
[Source: Oregon State University]