If ever you wanted a really unusual site for snorkelling, this is it - NOTE, it is not for diving for reasons explained later. Situated on Eil Malk Island, this saltwater lake was created millions of years ago after a submerged reef rose from the sea. It is now totally landlocked and isolated from the rest of the ocean, except for sea water that seeps into it through fissures in the limestone cliffs.
At that time, jellyfish were trapped in it and have now evolved to the point where they have no need to sting as there are no predators in this lake. There are probably at least two million of these creatures there now and snorkelling among them is definitely a strange and unnerving experience, until you realise that they can do you no harm.
They have algae that live in their cells and it is on these that the jellyfish live. Twice a day, the jellyfish swim across the lake to maximise the amount of sunlight they receive. Through a process of photosynthesis, the algae grow and at dusk, the jellyfish sink to a lower depth where the water is nitrogen rich. The absorbed nitrogen is what the algae live on. Both parties are thus "kept happy". It is at this lower depth, where the water has little oxygen and high concentrations of hydogen sulphide, that it becomes dangeous for humans. Hence, no diving. A wet suit will not give total protection against the elements here.
Although it's a bit of a hike up into the hills to reach the lake, it is an experience not to be missed.