In the age before longitude could be accurately measured, travelling on the high seas was almost as insanely dangerous as travelling into space.
The book Longitude: The True Story of a Lone Genius Who Solved the Greatest Scientific Problem of His Time by Dava Sobel, about the invention of the marine chronometer by John Harrison is a good read.
It was made into a C4 series starring Michael Gambon as Harrison which is available on youtube, and equally good.