TIme Outside

We have always been a fairly active family in the spring, summer and fall. When my daughters were toddlers they would play for 2-3 hours at a time in the back yard with the swings, sandbox, water table, sidewalk chalk and their trikes. As they grew older, the trikes turned into bikes, rollerblading and horse riding lessons for my oldest, ballet and tap for my youngest plus their swimming lessons and trips to the local lakes and town pools. BUT....in the last couple of years, they seem to want to spend more time inside. (mainly because of the computers and gameboys). So we have recently established a rule about healthier lifestyle actions: no computer on nice days unless doing a research project for homework. Email can be checked after homework is done, and then it is outdoors. The teenager in the house has much more homework, especially in the advanced classes she is taking, so her time outside is limited. However, she had a great idea for weekends: Dad will jog/run, mom and younger sister will bike and she will rollerblade or bike. (we bought her a new mountain bike last year). Once the youngest learns to use her bike with no training wheels, we will all go biking together on Cape Cod, on our town's biking trails and around our neighborhood.
We need to stay physically active. During the summer swimming and biking are easy things to do. We are doing this as a fitness plan but also to improve family relationships/time together. Of course we will continue to hike! (to the groans of the teenager...guess I will start letting her bring a friend along!). What are some ways you stay active in the summer?