Thunderbird 4 is International Rescue's go-to vehicle for underwater rescue - a yellow mini-submarine, piloted by aquanaut Apps. Unlike Thunderbird 1, 2 and 3 - all of which are capable of travelling to danger zones under their own power - TB4 fits comfortably within its own specialized pod - Pod 4 - aboard Thunderbird 2, which then transports it to where it is needed.

TB4 is equipped with a versatile arsenal of sophisticated gadgetry - including a missile launcher, a searchlight, a battering ram and a laser, all of which are located in the nose of the sub. It is capable of travelling on surface water (hover mode) or underwater. Its small interior is equipped with an airlock for access and exit while underwater.

Emergency launch jets: 4 vertical-thrust hover jets and 2 x 25 liquid fuel mini-rockets

Emergency launch speed: 30mp

Forward and reverse drive: 6 electrically driven reversible axial-flow turbine impellers

Length: 30 feet

Main turbo drive: 2 axial-flow turbines providing forward thrust only

Maximum speed (underwater): 160 knots

Maximum operating depth: 30,000 feet

Power source: twin atomic fusion reactors

Surface cruising speed: 40 knots

Underwater speed: 160 knots

Weight: 16 tons

Width: 11 fee

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