My brother in law and I have put together some fun, competitive activities for my 2 boys (ages 4 and 8). Take a look at this video of an indoor scavenger hunt I put together especially for those high humidity days. At the end of the video there is another one that shows some water activities we did. My kids are loving it. They can't wait for the days that we make it like camp for them.

https://youtu.be/ROwf-Yv6G_0