Dave and Ashlee invited us on a ‘float trip’ to a section of the Tanamá River at the observatory that they had been exploring for months now. The river passes through two large caves in this section.

We parked at the end of The Windiest Road In Puerto Rico just upriver of the observatory after leaving one car just downriver from the observatory. It was a one hour walk to the river. At the river, we clambered over boulders, swam and jumped a 15-foot waterfall over two hours before coming to the river cave beneath the observatory.

Here, the river enters a cave over100 feet high, with thigh-deep small rapids. Thousands of bats were on the ceiling. We waded forward through the cave, and after 15 minutes were able to see the distant light of the exit. We kept going until coming to a massive log jam, which we carefully swam into, climbed up onto the large trunks, and walked over to the other side. climbing over a log jam is extremely risky because if the logs shift and you fall between the logs, you'll almost certainly get trapped and drown.

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A gentle current floated us out of the main cave, and we inflated our packrafts on a pebble beach. Packrafts were probably unnecessary as one could easily walk and float this section with a life vest.

However, the packrafts were a ton of fun. Adventurers have taken packrafts to many remote places on earth, but I couldn't find much info online about packrafting Puerto Rico. In this section, they were adept and agile enough to negotiate the small rapids and numerous boulders. We went under a waterfall and passed through two more river caves.

After an hour, we saw a small group of tourists on inner tubes floating ahead of us. They got out and disappeared into the forest for the long walk back to the observatory, with us not far behind.

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Though the Tanamá is well known to Puerto Ricans, its caves are not. Some locals know of the tourist tubing trips, but are unaware of the massive and unique river caves in the more remote parts of the river.

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The river is also quite dangerous. Like most waterways in Puerto Rico, a few minutes of heavy rain can turn it into a raging torrent with deadly rapids. As some points, it's easy to walk out of the river, but in other sections you're fully hemmed in by cliffs and vegetation. The rocks are also incredibly slippery, and I'd bet there's been a number of injuries here from falls and broken limbs.

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Additionally, there are many dry caves that lie on or near the banks of the river. Some of them are only a few feet above the high-water level! Yet this river, virtually never more than a few miles from roads and homes, is basically a wilderness, ripe for discovery.