Way one: import photos — with the tide worked out
Most catch photos taken on a phone carry the GPS position and the exact date and time inside the file. Import them from your camera roll and each becomes a private spot on your map — and here's the part no shoebox of pins ever gave you: the app computes the tide and moon state for the moment each photo was taken. A snapper from a 25-year-old photo comes in knowing whether the tide was rising or falling that morning. Photo imports run up to 200 photos a day, and everything imported is private to you.