This is a map of locations extracted from digitized ship logs from 1750 to 1850. The database was compiled by a number of researchers and was made available as a resource for studying historical climate change.
It is a fairly unique dataset in both breadth and depth -- it covers 100 years of pre-industrial data, and contains often amusing notes recorded by sailors. The data also contains numerous fields for various meterological measurments, and one researcher was able to extract all mentions of naval battles, including a tussle with "a sea-monster of indeterminable size".
I have not done anything especially useful with the database yet, but I wanted to share this map of the full dataset and encourage anyone interested in climate science or maritime history to give it a look. This map was made using tippecanoe and Mapbox Studio.