Crystal Bay (Nusa Penida)

A sheltered bay on Nusa Penida's northwest coast where a sand floored channel slides past coral slopes to 30–40 m and a rocky islet at the entrance hides a shallow swim through cavern. From July to October, cold upwelling off the Lombok Strait pulls Mola alexandrini — the bumphead ocean sunfish, often topping 2 m — up from deep water to reef cleaning stations around 20–40 m, where bannerfish pick parasites from their flanks. The same chilled water can fire abrupt down currents along the outer channel. Glassy visibility, frequently past 25 m, gives the site its name.