Galápagos Marine Reserve in October

June through November delivers the best underwater visibility — sometimes reaching 100 feet at sites like Gordon Rocks. But the water's cold, around 65-70°F, so bring a thick wetsuit. This is hammerhead season when schools of hundreds gather at cleaning stations. December through May brings warmer water (75-80°F) and calmer seas, perfect for surface activities, but afternoon thunderstorms can cancel boat trips. Marine iguanas mate January through March — you'll see territorial battles both above and below water. Waved albatross return to Española April through December. But here's what tour operators won't tell you: August and September offer the best compromise of decent weather, good visibility, and fewer crowds. Book accommodations six months ahead for these months.