Photographs of the cenotes sampled in this study: cenote Dzenpolol (open type) (surface view (a), underwater view near the surface (b) and underwater view from the cavern zone (c)), cenote X’baba (open type) (surface view (d) and underwater view from the cavern zone (e)), cenote Polaban (cavern type) (view from the outside (f) and showing stairway into the water below (g)), cenote Santa María (well type) (h), cenote Xel Aktun (open type) (i), and cenote Ebis (well type) (showing ladder into the water below (j)).