For waterfalls and river caves, you might want to consider the Mtn Pine Ridge where you'll find the bulk of the countries waterfalls, including the 1000 Ft Falls (actually 1600 ft), the highest in Central America. Hidden Valley Inn has 7 private waterfalls on it's 7200 acre property and they offer a 3 night honeymoon package that includes an entire day on your own, with no one else around, at one of the waterfalls. Includes picnic lunch and sparkling wine. You can also paddle a canoe into Barton Creek underground river cave and visit the cavernous Rio Frio underground rive cave, all close by.
Rapelling at Caves branch with rustic accommodations on site.