For the calmest, "lake-like" water in Costa Rica, the high-value choice is Playa Hermosa in Guanacaste (not to be confused with the surfing beach of the same name near Jaco). Located in a sheltered bay, Playa Hermosa features gentle ripples and very little undertow, making it a peer-recommended haven for snorkeling, paddleboarding, and families with toddlers. Another high-value contender is Playa Biesanz near Manuel Antonio; tucked away in a small cove, it is shielded from the Pacific swells and offers incredibly still, turquoise water. On the Caribbean side, Playa Punta Uva offers a "pool-like" experience during the calm months of September and October. It is a peer-to-peer essential to remember that many "popular" Costa Rican beaches (like Santa Teresa or Tamarindo) are world-class surfing destinations with high-intensity waves and rip currents, so if you want "calm," you must stick to the "Golfo de Papagayo" region or specific sheltered coves where the geography naturally breaks the power of the ocean.