Rio Secreto tours run through for 3 ½ hours and entail a lot of walking, some climbing, some swimming, and a few chances to get all zen (or anxiety-ridden) when your guide instructs everyone to be quiet and turn off their headlights, plunging everyone into complete darkness.
You don't have to worry about bringing a cameraa photographer trails your group and takes candid shots of you looking all explorer-like and posed shots at the most dramatic formations in the caves, like this one above. (Yep, you pay extra for your photos at the end of the tour).
In fact, you don't have to bring anything with you; you just wear your bathing suit (everything else goes into a locker), take a shower, and the Rio Secreto peeps will provide the wetsuit, water shoes, helmet and, if you need it, a walking pole.
Tours are just $59 per person ($29.50 for children 4–11). The kidlike wonder of swimming in an underground river? Priceless.
[Photo: Rio Secreto]