bremont supermarine type 300 diver watch s301 bremont the new bremont supermarine type 300 range responds to a demand for a professional dive watch in a slightly smaller iteration. the watches’ namesake derives from the 1930’s aircraft company, supermarine, whose first ever spitfire prototype – the type 300 – led to one of britain’s most iconic aircraft. the new 40mm case of the type 300 is also slimmer being only 13mm from sapphire crystal to case back featuring a uni-directional ceramic rotating bezel.