It seems to me one could add sensors to existing cargo or other ships and have them collect data during their regular activities. You could pay them to deviate from their optimal course in a systematic way so as to cover more ocean with each voyage. No need to charter a ship or pay a crew to do this stuff.
This is similar to how OpenStreetMap uses GPS to gather mapping info from normal people making normal trips. Granted a lot of people go out of their way to gather extra data, but if everyone contributed a GPS track of every journey that would not be necessary.
Same thing, if every GA plane had a GPS and downward facing camera we could gather detailed imagery from much of the world.
TL;DR; Don't charter mapping expeditions, instead add automated mapping gear to vehicles that are already going places.
The only place that map showed with no traffic was sound of the horn of Africa, and the arctic. Between those latitudes there is traffic everywhere even if some is more sparse. You don't need to deviate far, increasing a long route by 5 percent can give a large lateral displacement. Remember, I said to pay them to do this too. Timely shipments are nice, but not always a priority.
This is similar to how OpenStreetMap uses GPS to gather mapping info from normal people making normal trips. Granted a lot of people go out of their way to gather extra data, but if everyone contributed a GPS track of every journey that would not be necessary.
Same thing, if every GA plane had a GPS and downward facing camera we could gather detailed imagery from much of the world.
TL;DR; Don't charter mapping expeditions, instead add automated mapping gear to vehicles that are already going places.