Because of poor weather further down firth, the Dutch submarine ZEELEEUW was forced to come as far as the Lower Loch Long area to allow a personnel transfer to take place. The diesel-electric submarine, one of the Royal Netherlands Navy's four such boats, was built by Rotterdam Dockyard and laid down in 1979. Launched in 1987, she was eventually commissioned in 1990. With their combined rudders and after hydroplanes mounted in a 'X' configuration, these submarines present a relatively unusual profile. Fitted to her conning tower is a snort diffuser, and ZEELEEUW and her sisters are amongst the world's most advanced conventional, non-nuclear submarines.