HAVE you have ever spent a day at Ocean Park trying to keep a whole family together and happy at the same time? You know what it is like: the older children demand one more ride on the rollercoaster and you are left to console a three-year-old who is complaining that his legs ache and he wants to go to the toilet. You, meanwhile, are leaning up against a railing aching to sit down and have a drink and wondering what is taking their father so long to get back with the ice cream. Ocean Park has solved all these problems with $50 million, 18 months work and a child's mind approach. Tomorrow, sees the opening of what will certainly be the park's most popular theme attraction - Kids' World. Built on 1.4 hectares, this expansion of the former Children's Adventure World features family rides, fun trains, recreational play areas, game stalls, a high diver performance pool and a dolphin ''university''. The chief executive of Ocean Park, Darrell Metzger, said the Kids' World was aimed at families with rides specifically for small children, and attractions and games of skill for the whole family. ''The merry-go-round and the theatre were already there but, apart from those, Ocean Park had nothing for the younger children,'' said Mr Metzger. ''Our new rides are aimed at the under-12 market, with attractions and activities for parents. ''We have a small boat ride for under eights to go on by themselves. It has jumping water, tunnels and music along the route. ''And even though the kids are in the canoe by themselves, there is a walkway right around so the parents don't actually leave their children. ''It's cute - fairly fast and a bit of a thrill for a little guy. The kids love it.'' Mr Metzger said the balloon Ferris wheel was the feature ride for families. A study showed that, on any day, 25 per cent of guests had ridden the Ferris wheel. Now, there was one for children, too. Another ride, the Clown-A-Round, is for those seven years old and younger. ''There are remote control cars and boats for the family and a castle play area where children can climb around the turrets, slip down the slides, walk over nets and crawl inside. ''We have other play areas, seating and a food area and a games area for the whole family,'' Mr Metzger said. Parents can watch their children at all times. Children under 12 are admitted free with a paying adult and the fun begins as soon as they enter the park. Clowns - a new attraction for Ocean Park - greet guests at the entrance. If Kids' World is the first stop on visit to Ocean Park, then there is no need to walk there. A bright red train travels from the lowlands, and circles the garden area before arriving at Kids' World. There is a total of four rides, two major play areas and about eight displays. ''Kids' World is a compact area. It is one of the best areas I have seen for children in any park,'' Mr Metzger said. ''Tiny Town World - a skilled games alley - will be the busiest area in peak times. ''For this reason, we have left plenty of room.'' The good news for hassled parents with children in tow is that, because of the large number of attractions, offspring will not be left standing in long queues. ''There will always be something for the kids to do,'' said Mr Metzger. ''Children don't like to wait. ''And, when there are shows, everyone will get a seat.'' Seat - the magic word when the day is hot and the young ones are getting grumpy. Central to the eating out area is the Sugar Plum House. Surrounding this is yet another seating area. And knowing well the ways of children, food stands, extra portable drink carts and additional toilet blocks have been incorporated into the Kids' World plan. Children under 12 make up 15 per cent of the visitors to Ocean Park. An added bonus to tomorrow's opening is operating hours will be extended. Ocean Park will open from 9 am to 9 pm daily with a 50 per cent discount after 5 pm when lights will add to the atmosphere. Mr Metzger said the discount was targeted at local residents rather than tourists. ''About 70 per cent of those coming to Ocean Park are local, with visitors making up the remainder,'' he said.