Cayo Largo's (and, perhaps, Cuba's) finest beach is the broad westward-facing Playa Sirena, where 2km of powdery white sand is wide enough to accommodate several football pitches. Tourists on day trips from Havana and Varadero are often brought here. Thanks to calm seas, nautical activities (kayaks, catamarans) are available. Set back from the beach there's a ranchón-style bar and restaurant, along with showers and toilets. It is the only Cayo Largo beach with shade.
Just southeast is Playa Paraíso, a narrower and less shady but nonetheless wonderful strip of sand, serviced by a small bar.