Cleethorpes is the seaside half of the Grimsby-Cleethorpes conurbation, and it feels very different from its fishing-port neighbour. The railway made it a resort in the 19th century, and the town still has that old English mixture of promenade, pier, chips, beach huts, amusement arcades, and wind coming straight off the North Sea.
The beach is the main event. At low tide the Humber pulls back a long way, leaving wet sand and mudflats that make the sky feel huge. Stay close to the marked beach and check tide times, because the water returns quickly through channels. Around the pier and central promenade the mood is busy and family-friendly; farther south the seafront opens out toward the boating lake, the Cleethorpes Coast Light Railway, and quieter dunes.
Cleethorpes is not grand, but it has more personality than many small resorts. You can ride steam trains on a 15-inch railway, stand on the Greenwich Meridian at the coast, look for waders and wildfowl around Tetney Marshes, and finish with fish and chips near the pier. It makes a good spare day from Lincolnshire, Hull, or the south bank of the Humber.