One of the most visited places is a local river called "Las Escobas". Its in the cerro San Gil, outside the urban area of Puerto Barrios and Santo Tomás de Castilla. The river is famous for its crystalline water and is very cold. It's in the middle of the jungle, but is very easy to reach it by a road or walking. Now "Las Escobas" has been reconstructed into a beautiful hiking and swimming area. If you're an adventurer and like to hike, there is a hiking trail, of course you have to be careful with the surrounding for there might be snakes and other amphibians.
The river has several natural pools, and they look like paradise.
But check the weather report before going there. If it has been raining in recent days, the water will be dirty. It's not polluted, but it isn't nice to take a bath in.
If you don't feel like traveling for a few hours then you can just stay inside the city. There you can walk to the two parks that the city has. One is located in the old part of Puerto Barrios, its name is Tecun Uman. This park is right in front of the "Hotel del Norte." Recent construction has been made to this park, and now cars and motocycles can go to a paves terrace overlooking the ocean called "El Malecon." The other park is located on the opposite site, this park is called "Reina Barrios" There is a large outside theatre shaped like a shell, known as "La Concha Acústica".
Now if you feel like cooling off from the hot sun, there is a mall called "La Pradera" located outside Puerto Barrios going to Santo Thomas. There you can find a foodcourt with McDonalds, Pollo Campero, Domino's Pizza, Saritas ice cream parlor, and many more different stationeries. There are clothing stores such as Gap, Adidas, and other local stores. There is also a game place near the foodcourt where you can play arcade games, air hockey, and ride a small carousel.
Puerto Barrios is a very nice place to hang around, to meet locals, enjoy the small citylife, go dancing, ...