Oceanarium - Also in Bournemouth by the pier. They have penguins and giant turtles and an underwater tunnel. Great for if the rain hits while you're by the beach. Just beside Bournemouth Pier and the lower gardens by the beach front.
Bike hire - Just 1/4 mile to the left hand side of Bournemouth Pier (if you're looking at the sea) is a great bike hire shop 'Front Bike Hire' where you can rent the bikes for 1 hour, 3 hours or the whole day. They hire out children's trailers too which are perfect for lugging around a picnic! (Or younger children who can't ride) Bournemouth seafront, Undercliff Dr, Bournemouth BH2 5AA
There are loads of places you can bike off to but if you turn right at Bournemouth pier and bike all the way down to sandbanks where the promenade stops there's a place called 'Jazz cafe' which serves ice cream, lovely food and has live jazz on a Sunday afternoon and in the evenings.
Also check out:
Also, don't forget that from November through December, Bournemouth (Usually - Covid pending!) has a 'Winter Wonderland' with an alpine lodge German Bar serving Mulled wine, a ski resort style Ice rink, a large festive German Market and a trail of beautiful light displays going down the high streets and through the gardens to the pier front.