Season at a glance: scalloped hammerheads are seen at Wolf and Darwin mainly from July to November, are largely absent between March and June, and appear in smaller numbers from December to April. The best overall dive season is June to November.
Wolf and Darwin are the two islands most closely tied to hammerhead sightings in the Galápagos, with Roca Redonda as a secondary site and occasional encounters further south around Floreana, North Seymour and Genovesa. The species most guests come for is the scalloped hammerhead, now considered critically endangered — though Galápagos sharks, silky sharks and whale sharks regularly turn up in the same water.
The single biggest factor in how many hammerheads a diver sees is the season, and the difference is not subtle. During the cold season, roughly June through October, water temperatures sit around 16–24°C and tracking studies have found that around 90% of tagged sharks stay inside the marine reserve during this period — dive counts of over 100 hammerheads in a single hour have been recorded at the best sites. May and November are transition months, with reserve residency dropping to around 65% and sightings becoming less predictable. By the warm season, December through April, water warms to 24–27°C and only around 30% of tracked sharks remain in the reserve; March through May is typically the weakest stretch of the year for hammerhead encounters.
This pattern isn't guesswork — it comes from telemetry research (including work published by Peñaherrera-Palma and colleagues in 2016) that tagged individual sharks and tracked how much time they actually spent inside versus outside the reserve boundary, backed up by ongoing visual census surveys from divers and researchers.
The reserve's protections matter here for a practical reason beyond sightings: pregnant females are known to use these waters, and the area is one of the few places scalloped hammerheads get real protection from fishing pressure. Responsible operators reinforce that with straightforward in-water rules — no touching, no feeding — rather than treating the sharks as a photo prop.
Source: adapted from Galápagos Shark Diving's own published article on the best time to dive with hammerhead sharks.