Hull, or officially calling it, Kingston Upon Hull, is a medium-sized city that lies on the East Yorkshire coast, near the mouth of the river Humber (this is confusing as the name of the city refers to a much smaller river, i.e. Hull, that flows through the city).
Hull has long been considered a rather grim backwater, both on the account of poverty of its inhabitants and being very out of the way to anywhere on the east coast. As many such places, this reputation is not entirely deserved, and Hull has several attractions as well as a character all of its own, definitely Northern and with a strong maritime element (it's still a commercial port and has a ferry connection to Holland). Additionally, it has undergone a bit of a regeneration and reinvention more recently (like several other northern cities).
It's hard to judge, however, whether the city is worth making a special trip, even if you are touring the north of England and as I said before, it's not really on the way anywhere else (unless you are taking a ferry to Rotterdam). Still, it's not too far from York which is a definite A-list destination. Also, if you have a specific interest in any of the attractions (The Deep being a prime candidate), it's obviously a place to go, and neither as far or as strange as it might initially appear.
Hull's tourist image is largely based on its maritime and more generally sea connection, and its attractions are often of such a maritime character. This theme has also been followed in the new and regenerated developments in the city centre.
Chief attractions in Hull include:
Streetlife Museum of Transport, with vehicles of all kinds from carriages and trams to fishing boast, as well as recreated scenes of olden-days street life. Free!
The Deep, Hull's own swanky aquarium with many interactive displays and tanks you can (kind-of) walk through. Expensive.
Hull & East Riding Museum, covering mostly natural and social history of the region, a good-standard regional museum with attractive displays from mammoths to whaling; and free. Visit if you have time.
Maritime Museum, with detailed displays on Hull's maritime history. A bit old-fashioned, but still good and free too.
Arctic Corsair, a museum based on an original fishing trawler (that was working until the 1980s) and an illuminating insight into the life of fishermen and the source of our daily fish & chips, tours by people who used to worked on the trawlers.
Wilberforce House Museum, devoted to life of an anti-slave-trade campaigner. Also free.
Ferens Art Gallery, surprisingly good local art gallery with highlights by Hals, Canaletto, Hockney, Helen Chadwick and special children's gallery for 6 to 10 year olds. The café is good too.
For added fun, follow the Seven Seas Fish Trail that takes you round Hull's centre's main attractions.
Nearby is the Humber Bridge, once a longest single-span suspension bridge in the world, a magnificent construction over the flats of Humber estuary, but a bit pointless one (not many people actually live on the other side). On the other side, the town of Beverley is an attractive one itself but the reason to visit is the Beverley Minster, a pile of golden Gothic stone.