Take a Short Walk to a Historic Train Tunnel

The Túnel de Guajataca in Isabela is a very well know tourist destination. It was part of the old train system that carried people, sugar cane, and the mail, and ran around a good part of the island. However, there is another, lesser known train tunnel called Túnel Negro (or Túnel Obscura or the Dark Tunnel) that you can visit which is very close by in Quebradillas.

Túnel Negro de Guajataca

In order to make the railroad go completely from San Juan to Ponce, The American Railroad Company of Porto Rico cut these 2 “twin” tunnels through the limestone and connected them by building a large metal bridge over the Río Guajataca. The Túnel Negro was built in 1906, and it is longer than the Guajataca Tunnel. It has a pretty sharp curve in it, so it is dark when you go through it (thus the name!).

Túnel Negro de Guajataca

To get to this tunnel, there is a nice walk in a shaded forest along a dirt trail. The trail is a little over a half mile one way, so it is a leisurely 20-minute walk, with only one part that goes uphill (and it is not too steep). The trail follows the Guajataca River, which is a beautiful place to hop in and enjoy! You will probably see people kayaking or swimming along the way.

Túnel Negro de Guajataca

As you continue along the trail, you will pass a large stone bridge foundation on your left. This was the base of the old metal bridge. Soon after this, the trail will curve to the left, and go up the hill. You will arrive at the tunnel shortly after that curve. Walk through the tunnel, it will be dark but not for too long. The tunnel is about 500 feet long and open on both ends, so you will soon see the light from the other end. You may hear bats in there.

Túnel Negro de Guajataca

These trails are used by mountain bikers, so you may see other trails here and there off to the side of the main trail. The trail continues after you exit through the tunnel. You can take it all the way to the end, which will put you on Route 2 about 600 meters north of where you parked — so you can just walk down the shoulder to your car. Otherwise, you will need to backtrack the same trail you took up. We found the trail along the river was cooler than the trail up top. And retracing your path will give you another chance to go swimming in the river!

On a historic note, there was a train accident at this tunnel on 06 September 1921. The train derailed, killing a couple people. There used to be a plaque memorializing the accident, but it is long gone. There is a newspaper article about the accident.


There is no cost to do this walk.

Visit the tunnel during daylight hours.

Allow about 1 hour, or longer if you plan to play in the river.

Bring a flashlight to us in the tunnel.

Parking and the trailhead for Túnel Negro is on the northbound side of Route 2, around KM 104.3, in Quebradillas. It is a dirt “parking area” on the side of the road. There is usually a food truck parked there. To get to the trail, go over or around the barrier, and then follow the trail along the river.

Click on a placename below to view the location on Google Maps ...

PuertoRicoDayTrips.com assumes no responsibility regarding your safety when participating in the activities described in this article. Please use common sense! If your mother or that little voice in your head tells you that you are about to do something stupid … then don't do it! Read more about Safety →

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