I just hear more and more good things about Idaho, The dirt bike riding opportunies are said to be exquisite, and highly technical. But still, I've got all this salt water in my veins...
I took my wife out to Craters of the Moon for her birthday today. We spent a fair amount of time exploring Boy Scout cave and Beauty Cave. The digital pictures had phenomenal colors. We also walked out to see the tree molds (tree impressions left in cooling lava flows).
You can take your dirt bike for a little "mountain biking" just south of Pocatello. Starting at the parking lot at 6600 ft, you can wind you way up the trail to the top of Scout Mountain at 8750 ft.
You could substitute fresh water for the salty stuff. My next door neight has been running off multiple times each week with a trailer full of "SeaDoo" jet skis. That same trailer is loaded with snow mobiles in the winter. If fishing is your style, there is abundant fishing in lakes and streams. You can hop on an inner tube in Lava Hot Springs and float a couple miles down the Portneuf river. If you would rather soak in the geothermal pools, that is available all year long.
I live 154 miles from Yellowstone National Park. My wife and I go there every 2 weeks...except that we decided to climb cinder cones and go caving at Craters of the Moon the last two weekends.
In winter, you can go alpine skiing at Pebble Creek (15 miles south) or cross country skiing at Mink Creek (11 miles south). I prefer to run up to the outdoor range and knock over some silhouettes and punch paper. Other in the area satisfy themselves hunting elk, deer, moose, mountain lions and black bears. There are gun and archery season...as you see fit.
I can't say I miss the salt water.