This 54m waterfall on the Argyle River is Tobago's highest, cascading down three distinct levels, each with its own pool of spring water, which you can swim in. From the parking lot, it's a 20-minute hike up. The entry fee includes an authorized guide who will lead the way and point out things of interest (it's usual to leave a tip). The path is easy to follow independently, though it can get slippery after rain (which also turns the pools a muddy brown).
There's a breezy open-sided cafe adjacent to the car park; and decent restrooms.