The act of masturbation in a semi-aquatic territory.

Open to both genders, a marine wank is most commonly (but certainly not exclusively) performed in the bath.
It is reserved for only the most progressive of wankers, the true cream of the crop. Those with a real appetite for their own genetalia.

Other more uncommon places to marine wank include public swimming pools, lidos, paddling pools*, ponds and lakes.

There are unconfirmed tales of people becoming addicted to marine masturbation. It is reported that people have become so desperate, they've been filling up sinks and dipping in their genitalia for a quick fix.

* please be noted that it is considered poor etiquette to marine wank in a paddling pool while children are present. You WILL go to jail, you dirty bastard.

to sport a boner, fly the sail at full mass, rock hard, etc.