Until further notice Park Service is allowing only groups with GUIDES to hike this trail.
The official distance from the Corcovado National Park boundary to the Los Patos Ranger Station is 2 kilometers. The trajectory described on this page is from the beginning of the ascent and apparently not from the boundary itself, since the distance documented was only 1.621 meters. This first section of trail inside Corcovado National Park is arguably the most arduous portion of the hike all the way to Sirena due to the fact that it is mostly uphill.
The trail location is shown in the map below, and the trail profile on the right reveals that the trail covers a total relief of 120 meters, though much of the elevation gained is lost coming into Los Patos Ranger Station.
The trail is most noteworthy for the series of steps that have been made to preserve the trail integrity. While this makes the hiking easier, a number of these have been washed away, and much of the trail is comprised of the red clay for which the Osa mountains are renowned. There are two unmarked forks on the trail, though in both cases, both forks converge again on the main trail so that it is pretty hard to go astray.
The Sendero Baco turns off to the left about 680 meters short of Los Patos. This trail loops to the south of the main trail and passes by a nice waterfall that is certainly worth the side trip for those planning on staying at Los Patos. The Baco trail rejoins the Los Patos-Sirena trail about 400 meters beyond the ranger station. For hikers that decide to take this side trail, it is advisable to backtrack to Los Patos to register with park rangers and to fill water bottles, since there are seventeen kilometers left to Sirena.
The route map from the Los Patos trail head to the Los Patos ranger statin is shown below with key features illustrated on the map. In the right hand column, greater descriptions are provided for each of the waypoints. The waypoints are listed in sequential order with mileage, elevation, and brief descriptions given.