One of the best times we ever had is when we use soy milk cartons to make boats. You can cut off one of the top panels of the carton to make the top. Then using paper towel rolls and cardboard you can make make sails. Then we used a small bin to hold the water and floated our boats. Some kids liked to make boats out of cardboard which is fine but they do tend to sink obviously.

Towards the end of the year we actually got a long bin and filled it with water and used a small fan to race the boats. The kids had a blast designing their own sails which they thought would help them win the race. Kids K-5 had a blast with it so I think it is great for all ages. Take care and enjoy
-mike