Jellyfish Lake
Known as a biological paradise the like of which you can find only at one other place on earth, this lake hosts a huge colony of jellyfish.
4 species of endemic jellyfish lives in this lagoon, including the upside down Cassiopeia Ornate,Mastigias Papua, Aurelia Aurita and Tripedalia Cystophora. These jellyfish are quite special; unlike their sea-living counterparts, they have been living in a lake, protected from their natural predators such as turtles and barracuda. Through time therefore, they have lost their ability to sting simply because they have had no need for them.
It's an otherworldly experience swimming with these jellyfish in hues of transparent pink and almost invisible blue as they gently pulsate and orb around you. Some find it eerie, others find it indescribably beautiful.
Try looking down into the depths of the lake where, among the green algae, you'll spot some snow white anemones. These are the new predators of the jellyfish; and any jellyfish which head down to the bottom of the lake are usually gobbled up by the anemones.
Lake Kakaban was created through a geological uplifting of the seabed over a period of 2,000,000 years, effectively landlocking 5 km² of sea water within a 50 metre high ridge. Over this long period of time the trapped marine life have adapted to stagnant, brackish and less saline water, low mineral levels and a simple food chain.
Fringed by mangrove and with a shallow bottom densely covered in green halimeda algae, the lake is also home to sea snakes, cardinalfish, gobies, tunicates, sea cucumbers, tube worms, crustaceans and other simple marine life forms.
Jellyfish Lake is actually a snorkelling site (you won't be allowed to dive here) comprising a lake in the middle of Kakaban Island, about 25 minutes from Sangalaki Island. You'll have to take a short trek through an untouched rainforest to the lake from the shore, after which you can snorkel to your hearts content.