⛰️ Roca Remolinos

Roca Remolinos is a submarine hill in Chacao Channel, Chile, notorious for being a major hazard for traffic along the channel. With its highest point at 20 metres (66 ft) below sea level, Roca Remolinos does not break the surface during ordinary low tides, but its top can occasionally be seen during extremely low tides. It is located at the narrowest part of the channel, about 700 metres (2,300 ft) from the nearest shore. Its northern slope reaches 16° while its southern one reaches 14°. The rock composition varies: four different horizontal layers have been identified, all of which are made of combinations of sand and silt cemented by ferric oxide. The uppermost 40 metres (130 ft) is a caprock layer made of medium to fine sandstone and is tuffite. Below this layer comes 35 metres (115 ft) of medium sandstone which in parts has low cementation levels. Below this there are 30 metres (98 ft) of well-cemented silt. Under the well-cemented silt there is at least 20 metres (66 ft) of densely compacted medium sand which is partly cemented.