Contrary to the folks who described this as a tourist trap, our family (we took our 2 twenty-something kids) thought this was well worth the trip and $. We had a wonderful guide and a group of about 8-10 tourists. It was a decent length hike and was over some very rocky terrain. Wear hiking shoes or sturdy sneakers for this part and bring water shoes for the swim as the rocks where you enter and can stand on are slippery. Our guide was great and provided a lot of info during our hike about the salt flats and other scenery. We were given a full 45 min to swim. Not too many fish to see, but a beautiful place to cool off and relax. You don't need to worry about "climbing over the rocks" to the other side as is described on some websites. They now have one side for land based tours and one side dedicated to cruise ships. The cost is reasonable (would have cost much more where we live in the Baltimore/DC area), the guide helpful in explaining what you see, and the "tour"necessary to control crowds and keep the environment safe.

Las grietas is a spectacular place, the day I went there was beautiful weather, there was sun and wind, to get into the water I had to wear a life jacket because the place is 12 meters deep, the water was freezing and very crystal clear,