Sci Fi/Horror TV series/drama from 70's or 80's.

[snorky]

This has been in my head for many years, but I have no idea of the title.
I'm certain that this was not a feature film, but a one off TV drama, or series of episodes.
I can't remember much, but I think it was set on or near some islands, Scottish possibly, and these strange beings appear from the sea and start freaking out the locals. They were either aliens, or some military project gone wrong. I'm also pretty sure that they used some kind of equipment to travel through the sea. I think this was from the 80's, but maybe the 70's. I would love to watch this again. Any ideas ?.

[Gerald Lovell]

Possibly THE NIGHTMARE MAN from 1981?

http://www.imdb.com/title/tt0170989/?ref_=nm_flmg_dr_5

[snorky]

This must be it ! - many thanks for that Gerald. It's was released by BBC Video a number of years ago, so I have a copy on order.