Yes, the ocean in Costa Rica is absolutely swimmable, but the "safety" of the swim depends entirely on which coast you are on and the specific beach you choose. On the Caribbean Coast (e.g., Puerto Viejo, Cahuita), the water is typically warmer and calmer, making it excellent for casual swimming and snorkeling, though it can become rough during the rainy season. On the Pacific Coast (e.g., Tamarindo, Santa Teresa, Manuel Antonio), the conditions vary wildly. While the Pacific offers world-class surfing, it is also notorious for rip currents, which are the leading cause of tourist drownings in the country. Beaches like Manuel Antonio are generally sheltered and safe for families, whereas beaches like Playa Grande or Dominical are better suited for experienced surfers rather than swimmers. A crucial tip for Costa Rica: very few beaches have lifeguards. You should always look for red flags posted on the sand, which indicate dangerous currents. If you aren't sure, ask a local "Sura" (surfer) or hotel staff. As long as you respect the power of the tide and avoid swimming alone at deserted "surf" beaches, the warm, tropical waters of Costa Rica are among the most beautiful places in the world to take a dip.