Technology on the river

Whenever I row a new river I always buy a paper map like this one RiverMaps Green River in Desolation & Gray Canyons Guide Book | NRS. The problem with it is I'm not always sure where I am on the map unless I'm super diligent at following every landmark and marked rapid. Are there any Apps out there that have names of rapids and descriptions on how to run a section of the river? I...

Technology on the river