December 6, 2025

Great white sharks are flocking to this island off Chatham

According to a local nonprofit that monitors shark activity, over half of Cape Cod’s great white shark sightings occurred last week close to an island off the coast of Chatham.

The group sSharktivityapp has been used to track 20 shark encounters and one seal attack since August 14, according to the Atlantic White Shark Conservancy. But there’s a lot of activity on South Monomoy Island in particular. Nearly two dozen great white shark sightings within a few hundred yards off the island have been reported since the beginning of August.

Eleven white sharks were sighted there between August 15 and August 17, indicating a spike in activity last week. According to the app, there was one shark spotted there on August 15, five on August 16, and five more on August 17. The majority of sharks, according to Sharktivity users, swam 50–100 yards off the eastern edge of the island, with others moving into the northern waters.

The sharks that frequent the Cape’s coastline are regularly tagged and named by the Chatham-based conservancy. After that, each tag sends real-time data straight to the Sharktivity app.

The conservancyQuadrilateral, a male shark that has been spotted multiple times this summer, was recently highlighted. On August 14, he was captured on camera close to Nauset Beach.

The 11-foot male white shark Quadrilateral was first discovered in 2017 and tagged in 2023. The group wrote that the shark’s four freckles behind its right gills resemble a quadrilateral.

The conservancy reports that on August 16, at noon, a seal near Nauset Beach North in Orleans was the last recent example of shark predation on Cape Cod. “Seal on sand bar with what looks to be a bite mark,” read a comment that included a picture from the app. Struggling but still alive.

As a freelance journalist, Morgan Rousseau covers a range of local and regional news for Boston.com.

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Janet Trew

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