From Cueva Llagar you paddle on in a westerly direction (its the only visible trail). You will find two bifurcations, the first one takes you to Yermes (you can connect to Grado from here), the second bifurcation takes you to Grado, or to Sama (and then to Trubia). All have some serious descending parts. I cant recommend climbing up the other way. The route that takes you to Grado is probably the most difficult one.