Whale sharks arrive in La Paz Bay each October and stay through April, following plankton blooms that turn the Sea of Cortez into one of the planet's richest feeding grounds. Rhincodon typus — the world's largest fish, reaching twelve metres and six tonnes — glides through these waters with mouths wide, filtering two thousand litres of seawater per hour. The bay's shallow continental shelf and nutrient upwellings create ideal conditions for the plankton aggregations that draw dozens of whale sharks within sight of the malecón. Snorkeling with whale sharks La Paz became a regulated activity in 2003 when Mexico designated the species as protected and established strict encounter protocols. Boats must maintain three-metre separation distances, snorkelers enter the water in pairs, and each vessel is limited to two in-water rotations per shark. The conservation fee — sixty pesos collected at departure — funds the monitoring program run by Universidad Autónoma de Baja California Sur, which has photo-identified over four hundred individuals since 2012. Researchers track migratory patterns, feeding behaviour, and site fidelity through dorsal fin markings and acoustic tagging. Most whale shark tours depart between seven and ten in the morning, when wind speeds average below fifteen knots and visibility extends past twenty metres. The route from Marina de La Paz follows the shallow bay northward toward Isla Espíritu Santo, scanning for the dark silhouettes and dorsal fins that break the surface. Encounters last thirty to forty-five minutes per shark, with boats repositioning to give multiple groups water time. Guides brief swimmers on approach angles — always from the side, never blocking the forward path — and hand signals for when to surface. The season peaks between December and February, when whale shark aggregations coincide with manta ray sightings and California sea lion colonies. Water temperature holds steady at twenty-two to twenty-four degrees Celsius, warm enough for three-millimetre wetsuits. The bay's protection from Pacific swells keeps conditions calm even when offshore winds pick up in the afternoon, though morning slots remain preferred for both visibility and animal activity.