Trinidad is home to the world only supply of pitch used in the surfacing of roads, the houses and roads around the lake all show signs of subsidence where the pitch is being mined, in the past it was indiscriminately mined but now it is ‘harvested’ only for certain periods of time and then allowed to regenerate and the life left of the pitch lake when visited is estimated to be 400 years.
The above link will give you a much better description than I could, but for the personal touch a group of us joined a tour to this lake
and were able to walk on its rubbery surface:
dip our toes on the sulpher rich waters which sit on its surface but since it was a fairly dry day they were not deep enough for swimming:
Then our guide showed us a spot where we could dig sticks in and pull up the sticky molten pitch:
this is why it is important to have a guide as there are areas where the pitch doesn’t have a ‘crust’ and it is easy to break through the surface and maybe you wouldn’t be as lucky as this young man who was pulled out alive if sticky!