Waterway Maps

Sorry I accidently posted this twice in the same category! I did a search in the message boards but didn’t see anything really. Hopefully I’m not asking the same question as many others. I’m wondering if anyone has any suggestions as to some waterway maps apps. I’m using an app called MyTrails but it seems to kill my battery(Note 9) and I can’t get it to stop running in the background(I think). I really want something that works like google maps but so far I have not found anything. Or the ones I have found I don’t know how to properly use. I’m a hiking trail guy so I’m use to finding maps pretty easy and following blazes, lol! Anyway thank in advance!