Caverns, tunnels and a column formation ('the Cathedral' and 'the Chapel') carved from solid marble by 6,000 years of wave…Caverns, tunnels and a column formation ('the Cathedral' and 'the Chapel') carved from solid marble by 6,000 years of wave action, with swirling grey-and-white stone reflecting glacial-blue water so that the walls appear to ripple. The colour comes from glacial flour suspended in the lake. The lake is South America's second largest and straddles Chile and Argentina. The marble peninsula has been worn into caves by wind-driven waves; the intensity of the blue changes through the season with meltwater volume. Repeated proposals to dam the Baker River downstream were defeated by the Patagonia Sin Represas campaign. Anchorage: Inland glacial lake, small-boat access from Puerto Río Tranquilo. Not a yacht destination; a shore-excursion showpiece. Hazards: No site-specific hazards noted, brief normally. More