Still working on my backlog of links. Here’s a collection of bathymetric maps — i.e., nautical maps showing soundings (depth) at various points — of Scottish freshwater lochs published in the early 20th Century. The survey was done from 1897 to 1909: “Over 10 years some 60,000 soundings were taken of all the major Scottish lochs, some 562 in total, resulting in the first detailed charts of all their depths.” The collection appears to be complete, and the map navigation is extremely zoomable. Via Here Be Dragons.