Chau Hiix is a Maya archaeological site reached from Crooked Tree by a long canoe trip through the wetland. It is not a casual ruins stop with a car park and ticket booth; the journey is part of the attraction, and conditions depend heavily on water levels and local arrangements.
When archaeologists or guides are available, the site gives Crooked Tree a second dimension beyond birdwatching. Ask locally before making plans, and expect a slow, weather-dependent day rather than a guaranteed packaged tour.