Lesbos Petrified Coast

On the western coast of Lesbos, the underwater extension of the UNESCO Petrified Forest of Lesbos geopark preserves fossil trunks of Miocene-era trees, formed when volcanic ash buried a coastal forest some 20 million years ago. The submerged section sits on the shallow shelf off Sigri and is accessible to recreational divers under guide supervision; fossil trunks lie partly exposed on the rocky substrate at depths between 10 and 25 metres. Because the entire area is a protected geological monument, divers may not touch, sample or remove anything; viewing only. Marine life on the surrounding reef includes dusky grouper, Mediterranean moray, common octopus, painted comber, ornate wrasse and scorpionfish, with the sandy patches between rock outcrops supporting common stingray. Visibility in the northern Aegean is moderate, typically 12 to 20 metres, and water temperatures cool earlier in autumn than the southern islands; June through October is the reliable dive window.