Chamal Mediwaka
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This is a beautiful waterfall and I think it is one of the most popular ones in Puerto Rico. Unfortunately it has been shut down since the Hurricane.
It is located at the end of the most popular trail in the El Yunque National Forest. The trail follows the course of the La Mina river, passing many tiny Cascades and tiny pools filled with cold and clear mountain water.
The trail begins at the Palo Colorado Information center located at PR 191, 12.2 KM mark. You will need special permission from the authorities to get there since it's the trail is closed down due to the hurricane.