I use Motion-X GPS. Now it has many map types, but not a strict topo with elevation lines like you might need in larger mountains. But it's got 11 other map types, terrain, satellite, road, hybrids from Bing, Apple, and Google maps.
No cell service needed, able to pre-load maps as needed. Or usually I just view and scroll around prior to a trip, and it keeps that loaded in memory with no other work by me.
It's a full featured gps program as strong as any standalone gps unit. Never use my garmin 76csx anymore. I do carry a brick charger as needed, and use airplane mode too.
There's lots of excellent options these days.