Brighton Marina is home to hundreds of sailing boats & dinghies, and offers great walks, as well entertainment, dining and retail. It's also the base for numerous boat & fishing tours around Brighton, along the coast and out to the Rampion Wind Farm. Great walks can be had though the Marina, watching the boats, or out along the outer sea wall at the far end, watching the numerous fishermen casting their lines & reeling in their fish. On a Sunday morning, there's usually a big Boot Fair on the roof of the multi-storey car park.
Entertainment wise, the Marina hosts the Cineworld cinema, bowling and a casino, plus there are a few shops dotted around, although the Marina is not really known for it's great shopping. Parking is easy and inexpensive/free, with a large multistory car park.
Restaurants and bars abound, along the Marina's edge, with outside tables overlooking the boats & the water, which can make for a lovely evening when the weather is fine. The choice of restaurants is mostly chains, so the food is usually decent, but nothing out of the ordinary. There are also a couple of good pubs at the Marina, The Master Mariner and a big Weatherspoons.