Selkie

Teenager Jamie moves with his mother, sister and grandfather to an island off the South Australian coast where mum has a job running a marine research station. To his discomfort, Jamie discovers he's a "selkie" - half human, half seal - that explains the webbing on his hands and also why he changes completely into a seal as soon as he hits water.

Doctor Who: The Invisible Enemy

A three-man rocket crew are nearly done with their mission to Titan Base until a course change puts the rocket in the path of a strange cloud in space. By the time they arrive, they have come under the control of a sentient virus which threatens the galaxy. When the TARDIS picks up an emergency message, it flies into the cloud, infecting the Doctor. To save himself and others, he must undertake a dangerous journey.