Landmark· Santorini (Thira)· Greece — Cyclades
Kolumbo Submarine Volcano
36° 31.0′ N · 25° 29.5′ E
An active submarine volcano about 8 km northeast of Cape Kolumbo on Santorini, its crater rim only about 10 m below the surface. In 1650 its pyroclastic flows crossed the sea and killed about seventy people on Santorini.
Practical
Wikipedia position (crater about 1.5 km across). Wikipedia gives the rim at about 10 m; sailingissues says about 17 m, 4 nm NE. It is not a keel hazard, but it is an active volcano: in 2022 researchers found a slowly filling magma chamber 2-4 km down (eruption 'not imminent'), and Turkish agencies warned in 2025 that the earthquake swarm could affect it. Watch for Port Authority or Coast Guard navigational warnings (VHF 12/16) about exclusion zones in this area, and do not loiter over the summit during seismic unrest.
Best for
Awareness when passing NE of Santorini toward Amorgos or Ios