Pitch Lake
A pitch lake is basically a naturally occurring lake of Asphalt or sometimes called Tar! Yes a variation of the same material which most streets are paved with. In fact, many of the first paved streets in New York, Washington DC, and many other east coast cities, used Asphalt from this deposit. It is the largest known deposit of Bitumen(Pitch/Asphalt) in the world. The better known La Brea Tar Pits in California in the U.S. are also pitch lakes. The pitch lakes in Trinidad are actively mined(evidence of which can be seen in the picture below), where the U.S. La Brea Tar Pits are mainly searched for the fossils of prehistoric animals and early human artifacts which became trapped in the thick sticky liquid over the millennia. Definitely a sight to see, stinky though it may be!
Grueslayer, CC BY-SA 4.0 <https://creativecommons.org/licenses/by-sa/4.0>, via Wikimedia Commons