We had a great visit to NH for a wedding and had a few hours to spend. We had 5 children ages 3 to 17 to entertain, so off we went to Ruggles Mine. It's not inexpensive (for 4 adults and the kids, admission was $176), but we all had fun. Bring your own flashlight, buckets (or sturdy bags) and hammers if you can. You can collect as many minerals and rocks and you can carry! There are caves to explore, dirt to play in and, of course, rocks to be mined. The boys (even the grown-up ones) all loved using the hammer to collect their treasures.