A traditional way of coaxing children into finishing their fish dinner has been to remind them of the hardships endured by the fishermen who put the portion on their plate: mountainous seas, freezing cold and so forth. It has seldom worked the National Fishing Heritage Centre at Grimsby doesn’t hide the fact that it was fishing that put the grim into Grimsby. While several rooms house interesting exhibits on the history of this most punishing industry, the best part is a series of tableaux that takes visitors to sea and home again in a Fifties trawler. Going back a decade, you can sample warfare on and beneath the waves. And on the full tour, a gnarled sea dog will tell you salty tales as look round a real trawler.

The tableaux show that life was tough not just for those who went to sea. A street scene features a pinafored woman “braiding” (mending) nets in her back yard - arduous and eventually crippling work, according to one wall display. Nearby, a man coughs and flushes the toilet in an outside privy. From an upstairs window another man gestures roughly to the woman. In the background, men’s taped reminiscences provide atmospheric detail. Nothing too explicit, but it’s pretty plain that women knew their place, which was to wait and hope that husbands and sons would return safely.

Two of the best tableaux show that they had good cause for anxiety. A deck clogged with ice chillingly evokes Arctic conditions, while a separate representation of topside activity during a raging storm has you wishing for some sea-sickness pills. As the floor moves this way and that, the deck plunges and rolls. The wind howls, metal groans and the sea crashes. But those on deck only have eyes for the “moneybag”, the net from which their catch spills into the hold.

The Second World War worsened a job that was dangerous enough in peacetime. In the Trawlers at War section visitors can take part not only in a simulated air attack on a trawler (tin hats provided) but, even more thrilling - or terrifying, depending on your nerves and imagination - wait grey-faced in a replica German submarine while the sonar pings from a British surface vessel foreshadow attack from depth charges. Sounds gratuitous? A guide who gives details of the horrors of death at sea makes sure it is anything but. By way of good organisation, an excellent resource pack and a wide variety of attractions - including lots of hands-on exhibits - the centre provides an exciting voyage of discovery, although it steers away from issues of sea-life conservation.

The National Marine Aquarium in Plymouth offers a far more sympathetic view of sea creatures (and a far lovelier outlook for visitors - the town harbour as opposed the Grimsby branch of Sainsbury’s). The aquarium nurtures sea creatures in conditions so spotless they should feel privileged. In fact, the design of the museum impresses rather more than its denizens. A steeply sloping sea bed in a long tank allows visitors to examine local estuary life from high and low angles. Some areas are designed to enable smaller children get a better look, for example at the residents of a large rock pool. Two massive tanks give the larger specimens ample fin room.

And teachers looking for additional information will appreciate some good wall displays as well as regular talks from experts on marine biology and the environment. With its sea cucumbers, crabs, anemones and starfish, the rock pool is a clear favourite with many, if not quite as much as the tanks that hold the bigger draws. But even these conger eel, turbot and thornback rays are dwarfed by the model whales suspended from the ceiling. Unfortunately, these likenesses merely remind you of the live creatures to be seen at more ambitious venues. The same is broadly true of the immense shark tank, which is like watching the occupants on a wide cinema screen. But these reef, sandbar and nurse sharks are strictly little league compared with such headliners as the tiger and the great white.

One group of small boys, their noses pressed against the tank, gleefully booed and hissed each passing shark. In the coral reef section, fish that might have been classified by wattage dazzled the same bunch into near silence. Labelling these things must have been like trying to bottle sunlight: even names such as pyjama cardinal fish, half and half goatfish, African pygmy angelfish don’t come near to evoking their palette. The same goes for another coral reef resident, the blue-spotted boxfish. A tapered, triangular body, flattened forehead and woebegone expression turns into one of nature’s practical jokes. I turned to a small boy who was also trying to puzzle it out. “Weird,” I ventured. “We-ird,” he replied. Enough said. Some thoughts run too deep for words.

National Fishing Heritage Centre, Alexandra Dock, Grimsby, DN31 1UZ. Tel: 01472 323345. Admission pound;1.35 per pupil; trawler visit only: pound;1.35;both, pound;2.45.One teacher free withparty of 15 or more. Book first. Pack: pound;5. Free preliminary teacher visit. n The National Marine Aquarium, The Fish Quay, Plymouth PL4 0LH. Tel: 01752 600301. Admission pound;2 per pupil, includes talk and teacher’s help sheets; “In-depth” visit: pound;3.50 per pupil includes tour and teacher-led session. One teacher place per seven primary pupils or 10 secondary. Book first. Pre-school children pound;1, pound;4.99accompanying adult.Free preliminary visits.

PLENTY OF FISHES IN THE SEA

* Weymouth Sea Life Park, Lodmoor Country Park, Weymouth, Dorset DT4 7SX. Tel: 01305 788255 * Hastings Sea Life Centre, Rock-a-Nore Road, Hastings, East Sussex PN34 3DW. Tel: 01424 718776.

* Bournemouth Oceanarium, Pier Approach, Bournemouth, Dorset. Tel:01202 311933 * Portsmouth Sea Life Centre, Clarence Esplanade, Southsea, Portsmouth. Tel: 01705 827261 * The National Sea Life Centre, The Water’s Edge, Brindley Place, Birmingham B12 HL. Tel: 0121 6334700 * The London Aquarium, County Hall, Riverside Buildings, London SE1 7PB. Tel: 0171 967 8000