This is a lot slower and less enjoyable than the other stories, but it's still good - shows the standards of this Fourth Doctor season.

The Fourth Doctor is a lot darker in this story - this era of the show doesn't really match with scary, ghost stories, so although its a nice change, this TARDIS team doesn't really fit in this story. The Doctor goes swimming, Romana uncovers secrets and K-9 gets taken over - again!

I liked how they used the sea life to threaten the submarine - it's used effectively, combined with aliens to create some interesting creatures. Stories always interest me when they use their setting to their advantage. However, the main threat - goblins and pixies - was very childish and boring.

It was very hard to tell whether they were on their explorer or the submarine, and I couldn't keep track of where everybody was, which was a little disappointing. It felt like they didn't put too much care and just decided to have two ships so it wouldn't just be a runaround one place.

The side characters were bland and uninteresting, yet again, and they coped with K-9 far too well...

A letdown after quite a few strong Fourth Doctor releases, but at least K-9 gets a bit to do here.