Outdoor things to do in Washington state?

me and my husband are very outdoors people and we find little trails to keep up busy but for our anniversary he told me to pick something well long story short i like (oceans, water falls, hot springs, hiking) but what i really want is a waterfall you could go swimming in some thing with not a lot of people (something like it) we live in the lacey/olympia area so nothing 3 hours away. we are new to WA and i don't know everything that is out here. HELP!