Wadi Shab in Oman, absolutely amazing place! Definitely recommend. And, it's for free (you have to pay just 1 OMR for a boat to get you across the river) then you have to walk for about 40 min through a canyon and swim little bit (so don't take any cameras or phone with you) At the end you have to swim into the cave and you'll reach beautiful waterfalls and amazing place for jumping.