Evans Capacitor Company, whose energy-dense Hybrid capacitors are found on space shuttles and advanced aircraft, has made these capacitors available for deepwater use. Tested to 10,000 psi and impervious to salt water, these tantalum Evans Hybrid capacitors provide up to two joules/second and 0.5 joules/g. They have more than 10 times the energy density of aluminum capacitors.
Evanscaps filter power, fire pulses, correct power factors and allow submersibles to ride through critical power interruptions. Hermetically sealed, they are available with four-pin mounts or threaded mounting studs. They are available in both standard and custom configurations and can be combined in banks.
(www.evanscap.com/deepwater.html)