Aktun-Chen is a privately managed nature reserve about 7 km south of Puerto Aventuras on the highway toward Tulum. The centrepiece is a dry cave system — one of the larger accessible dry caves on the Yucatán Peninsula — with stalactites, stalagmites, and an emerald-green cenote at the end of the main passage. Guided tours take about 45 minutes and do not require any climbing or crawling.
Above ground, the reserve runs a zip-line circuit through the jungle canopy. It is not a particularly extreme operation — the focus is on the trees and the wildlife visible from the platforms — but the canopy perspective on the Yucatecan jungle is worthwhile. Spider monkeys, coatis, and various birds are regularly spotted.
The cave tour and the zip-line can be done as a combination package. The reserve is quieter than the big cenote complexes to the north and the guides are genuinely knowledgeable about the local ecosystem. Best visited in the morning before the larger tour groups arrive from Playa del Carmen.