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Crystal Bay

By 22 March 2017January 30th, 2024Underwater Life

Mola at Crystal BayWhen thinking about diving around Nusa Penida, it is likely that you have heard of the famous Crystal Bay.

Crystal Bay is famous for many reasons; It is a close site to the manta dive sites, making it an easy 2nd dive for dive centres. Crystal Bay is known for its crystal clear visibility and extreme thermoclines.

The biggest reason a lot of people have heard of it and the reason most people want to dive it, is because of the chance to see the Mola.

Cyrstal Bay is also famous for some ‘interesting’ reasons as well. We are going to cover all the reasons this site is famous; from the good, the bad and the ugly Mola.

Mola or Mola Mola?

First lets clear up a few things about the Mola. To call the Molas that we get in the waters around Lembongan as Mola Mola, is incorrect. The Molas that we see while diving in Lembongan are in fact, Mola Ramsayi.

Mola Mola, or Sun Fish is a type of Mola but it is different to the ones we get here. The main differences between the two are the size and the colouring of the skin. Mola Ramsayi are typical larger with more darker shading.


The extreme thermoclines that we experience in Crystal Bay, are one of the main reasons we often see molas there.

Open to the channel between Penida and Ceningan island, Crystal bay runs from shallow sand to deep open channel. The upwelling currents push the cooler water up from the deep, into shallower waters. A thermociline is where warmer water currents meet with cooler water currents. During a dive, as you pass through the water column getting deeper, you can run into these colder parts of water.

It is possible to have some extreme thermocilines. The first 20 meters of water, you could have 28 degrees but once you get deeper, the water temperature could drop as low as 18 degrees. It is a bit of a shock hitting that cold water. When you are on your way back up, and you enter into 28 degrees, it is like passing through into a hot bath.

It is these cool thermocilines that bring the molas from the deeper water. You are more likely to see the Mola when the water temperature drops. Molas spend most of their time in deeper, cooler waters. When the top water column starts to cool due to thermocilines, the Molas come up shallower, allowing divers to see them.

Is Crystal Bay the only place to see Molas around Lembongan?

Crystal Bay is not the only place that has these thermocilines and it is not the only place that we see the Mola. But Crystal Bay’s thermocilines are more extreme compared to other Lembongan sites.

All the dive sites through the channel and the sites along the north coast of Penida, have Mola sightings.

Crystal Bay MapThe main reason the Molas do come up to shallower waters, is to be cleaned by the reef fish. There is one main cleaning station, just off the corner of the small island in Crystal Bay. During Mola season, it is often that you will spot many divers waiting at this corner, looking into the blue for the chance to see one of these crazy creatures.

It is also these thermocilines that give Crystal Bay, the reputation of ‘crystal clear water’. This cooler water is normally clearer and cleaner then the shallower water. The visibility is normally better then in the warmer water.

What to look out for:

With the upwellings that push into Crystal Bay and with it being so open to the channel, it is possible to have some ‘interesting’ currents around the site. If you dive the site in the correct way and on the right tides, the site is generally safe.

The bay area, on the sand, in the shallows, is a protected part of the site and is often used by many dive centres for divers on courses.

The small gap between the small island and the beach, is very shallow and opens to the channel, this is one area that we do not dive. This narrow and shallow channel can have some fast moving currents making it not a good area for coral growth and not fun to dive.

The other area where it is possible to have strong currents is on the outside of the small island, as it is at the start of the channel. A current check is very important before leaving the bay area and exploring the outside. If the current is to strong, your guide will keep you in the more protected bay area.

It is possible to have almost no current on the outside, during these times, it gives divers the great chance to explore the deeper side of Crystal Bay.

Twin Island Dive and Crystal Bay:

Twin Island Dive’s guides are very experienced with diving in Crystal Bay and will be able to guide you through the site, nice and easily.

Keep in mind, when asking to go to dive sites in Lembongan, that Crystal Bay is not the only place around Lembongan where you have the chance to see the Mola. During high season, it is possible to have 40+ boats in the bay area, diving the small site. Twin Island Dive try to avoid Crystal Bay on days like this.Crystal Bay Photo

During the high season months, if you do not dive at Crystal Bay, don’t take it as a bad thing, chances are Twin Island Dive took you to another site, where you have the chance to see a Mola and less divers underwater.
For more information about the dive sites around Lembongan, checkout our dive site page.

To have the chance to see the Mola!