Stadikka, Finland's home of Speedos. This Olympic length swimming pool is a mecca on hot days in the school holidays. It opens when the warmer summer months (theoretically) approach.
Come here to get your fitness fix on a nice overcast day when the lanes aren't too crowded. You can lie on the grass and soak up the rays - if there are any - or take a position on the grandstand and watch the mums and grannies aqua-running back and forth. Decent saunas too.
It gets super busy before and after working hours so the best time to hit the pool is early afternoon.