Mangapwani Coral Cave is a ways up the coast from Stone Town so not easy to get to unless you have a driver or a car.
But it is an important site as part of the history of the slave trade in Zanzibar.
There are steps how to get into the cave but it is still a bit tricky and you have to walk carefully if you move around in the cave past the steps.
Your guide will tell you of the slave trade and how slaves were just dropped into the cave(no steps then) and taken out through tunnels to the beach where they would be loaded onto dhows for shipping away.
they also take you through the brush to see where the exit from the cave is located. rather a somber trip and visit but again, historic and unique for the area.
There was supposed to be a fee but we only had to give our guide a tip and didn't pay anything else.
There are no facilities there at all and it is certainly not accessible for anyone who can't climb down the stairs on their own.