Cromer (seen here) is a seaside resort town on Norfolk's northern coast. It is a Victorian-era resort town, and I believe that the pointy thing sticking into the water is the amusement pier, pictures of which can be found here
To my knowledge, the only intersection between Doctor Who and Cromer is The brigadier's remark about mistaking an alien landscape for the beach nearby the town in The Three Doctors.
Many American fans have interpreted the line as being "I think that's chroma." They use this as an example of the show's willingness to break the fourth wall - chroma-key is the American term for what the British call CSO (Colour separation Overlay). They find this to be even funnier than the original intended joke. Such is life.
I was asleep when I visited Cromer. I was having a nap in the back seat of a car when all the awake people decided to take a detour along the coast, instead of heading straight back to the house we were staying at. Later on, when I was shown all the places I had slept through, I remarked that I would liked to have been woken up for Cromer.
"Why Cromer?" I was asked.
"It's supposed to look like the interior of a black hole."
It was at this moment that there was a silent agreement that we all should drop the subject.