La Pesca is 50 kilometers east of Soto La Marina on Highway 70. There's no large airport, so it has to be reached either by car or bus. If coming by car from Matamoros, follow Highway 101 south for about 180 kilometers and turn left onto Highway 180, about 20 kilometers south of the small town of Las Norias. The turn-off is well marked. Another 80 kilometers will take you to Soto La Marina, where you'll take a left onto Highway 70, which will eventually end right on the beach at La Pesca. Highway 101 south of Matamoros is a nice four-lane highway as far as you'll take it, but Highway 180 and Highway 70 are both part new four-lane highway and part old two-lane highway. Part of Tamaulipas state's development plan for La Pesca is completing new four-lane road construction all the way to town, though, and it might be done as early as 2009.
If you're coming from Texas, remember that you'll need an importation permit from Banjercito to bring your car into Mexico, as well as temporary auto insurance seguros de autos that covers Mexico, both of which you can get fairly quickly and efficiently right as you cross the border into Mexico. Most border crossing will have a building immediately to your right coming into the Mexican side which will house all the offices you'd need to visit.
If you're not used to driving in Mexico, keep a keen eye out for speed bumps topes, which are used liberally in towns to slow down traffic and can often be unmarked and unpainted.
You can catch buses to La Pesca from the bus station in Ciudad Victoria.