Jellyfish Lake is one of a kind.
It's a place where 20 million non-stinging jellyfish roam freely alongside tourists and locals. From above, the 12-acre lake in Palau -- a remote island nation 550 miles southeast of the Philippines -- looks like any other lake. The water's thick, brownish appearance doesn't, at first glance, exactly entice visitors to enter.
Once you dive in, however, and swim deeper below, the brown sludge is replaced by a greenish milk-tea type color and, soon, jellyfish of all sizes appear out of the shadows. And then, what had seemed an ordinary lake can begin to more resemble a fantasy world.
That's how underwater photographer Sarosh Jacob describes Jellyfish Lake. Since 2010, Jacob has traveled to some of the world's most remote places to photograph marine life under threat from climate change and overfishing. He visited Jellyfish Lake in 2011, after having first seen it in a BBC documentary years earlier. He and his girlfriend got engaged in Palau on that trip. They are both avid divers, and Jellyfish Lake's surreal beauty, at least on television, appeared unlike anything they had ever seen.
"We knew we had to go," Jacob told NBC News. "From a photography point of view, I knew it would be something special."
Jellyfish Lake's beauty has confounded visitors for decades. Known to locals as Ongeim'l Tketau, it is one of Palau's 70 saltwater lakes, all of which are connected through fissures in the islands' porous limestone.
The life of the jellyfish there resemble Darwin's finches, used as a model for his theory of the origin of the species, according to the National Wildlife Federation. Five of the lakes contain one-of-a-kind species of jellyfish.
Only one of the lakes, Jellyfish Lake, is open to the public. The others are protected natural habitats, untouched by man. Some experts say that, after the last Ice Age, sea levels rose and trapped the jellyfish in the lake, leaving them without natural predators.
Jacob's photography from the lake, taken on two separate occasions as he swam alongside millions of jellyfish, takes viewers along with him as the creatures follow the sunlight to their next destination. Traveling in packs, they can appear almost infinite in number. For Jacob, the graceful jellyfish in Palau are vivid reminders of the importance of conservation.
As more people hear about Jellyfish Lake, more tourists visit each year. That additional stress, combined with the effects of climate change, could take a toll on the jellyfish population that has lived there for thousands of years.
"The lake is one of those places that allows people to witness the wonders of marine life," Jacob said. "But my photography, hopefully, inspires others to care about the environment there and the survival of the jellyfish."