For being such a small country, Costa Rica's beaches cover 1100 miles of coastline define a large portion of its landscape and way of life.
The main attraction of visiting beaches in Costa Rica is the natural beauty. Even at the most “developed” beach towns like Jaco and Tamarindo, you can hear howler monkeys calling in the distance, spot scarlet macaws high in an almond tree or stroll the palm-lined coast looking for hermit crabs and seashells. If you want less of a crowd, a secluded beach is never far away.
If you want to get as far off the grid as possible, try hopping down to the Osa Peninsula on a quick 45 minute flight where you'll find miles of untouched coastline. For fishermen or naturalists, a trip to the north Caribbean's maze of canals and empty coasts provide the best sport fishing. The Nicoya Peninsula with small towns like Santa Teresa or Nosara provide are some of the best surfing, where the surf vibe is as big as the waves.
To get the most out of your day, wear LOTS of sunblock no matter your complexion, even dark-skinned Ticos burn. Drink lots of fluids to avoid dehydration; fresh coconut water right from the coconut should do the trick. Watch for riptides. If there isn't a lifeguard or a surfer nearby, stay where you can firmly touch the ground. Don't forget to have fun and buy your souvenirs at the beach where the prices are more reasonable than the airport.