Whenever you're out and about in nature you should have a set of maps with you. Depending on the circumstances, offline GPS on your phone is usually your best bet. Getting maps offline isn't difficult, at least not the way I've figured out how to do it. If you're going to be out for more than a few days I'd recommend bringing paper maps with you. I will not be getting into how to use paper maps. You should take a class or watch a lot of youtube videos on how to do orienteering. I use an app called Backcountry Navigator. It's developed by a person in Camas, Washington, which I like. I don't really like apps like Onx because of a few reasons. The main one is that Onx has basically stolen a ton of information from public data sets and presented it as their own while charging subscription fees. That violates the open source/community value that a lot of GIS(mapping) operates on. Gaia is a great alternative. One thing to know and remember is that these apps are just front ends for data. You should never be forced to use a specific app or program to access GIS datasets. When I say dataset I mean maps, overlays/information, land ownership, etc. Traditionally, these are not tied to any one app or program. What you do instead is you find a front end app/program that you like to use and then you purchase access to your data/map sets. You can change your front end and keep your access to these data sets. This is important. If you're familiar with code repositories or anything like that this should make sense. TLDR: Your app just downloads data and determines how you interact with the data. The data is the same between apps. In this example I will be exporting the Run The Rock 50k GPX track from caltopo.com and then importing that information into BackCountry Navigator. Once I do that I'll be downloading the maps that I need for this race. The GPX is optional if you're just out and about exploring with no destination or set path.
A GPX file is NOT required for this. If you don't need to see a route or track then you can skip a large amount of this. Let's go get our GPX. I do this by visiting Alpine Running's page for the race, then going over to the caltopo that the race directors Trevor/Janessa provide for the runners. https://caltopo.com/m/78QL3 is our course. As you can see in the image below, we have a track(the red line) and markers(start/finish/aid stations). We can export all of this via GPX. We do that by clicking on the folder button the left which I've circled in green.
Once we click on that it opens up a new menu with options. The important thing about exporting is your type. The two most common are JSON format and GPX format. We'll use GPX for this.
Select the data you want to export. In this instance we want everything but some race directors go wild with their information so you may occasionally need to unselect a lot of stuff. It varies, you learn what you like. When you are ready click "Export" on the top of the Map Items window.
I have to confirm the download.
So now we go back to our front end app, which is BackCountry Navigator for me. I've already placed my map on Smith Rock. As you can see there are no tracks or markers. Let's change that.
In the map screen for BCN there is a hamburger menu in the top left. I click that which opens this menu. I select Trip Database.
Now we select Import because we're importing the GPX that we exported from Caltopo. I didn't include screenshots of selecting the .gpx file. This will vary depending on device and it's simple enough to figure out.
Now on the map screen we have our track and markers! This tells us what we need to download. On the top of this map screen is the Map Layers menu, represented by stacks of paper/maps.
Inside the Map Layers menu there is a "Select Areas for Download" option. That's what we want.
I select what I want to download and that's shown to me with the blue squares. There is one thing to remember when downloading from GIS sources: everything is downloaded by tiles. A tile is one square of the GIS grid. Everything is organized because of this grid. You can't download parts of tiles, generally. When downloading more is not always better. You'll see in the next step.
Now we can jump back to our map screen. As you can see the map looks a bit different. This is because I'm in offline mode and it isn't showing data it doesn't have. But do you also see how it downloaded more than the blue squares? This is because of tiles. This means my blue download markers included partial tiles. Since we can't download partial tiles we have extra data. This usually doesn't make a huge difference, but it can, so be aware of it.
And that's basically it. Every front end app is a bit different, so play around with it. Use your app for a lil while before relying on it. Never go out into nature without testing.
Once we click on that it opens up a new menu with options. The important thing about exporting is your type. The two most common are JSON format and GPX format. We'll use GPX for this. 
Select the data you want to export. In this instance we want everything but some race directors go wild with their information so you may occasionally need to unselect a lot of stuff. It varies, you learn what you like. When you are ready click "Export" on the top of the Map Items window. 
I have to confirm the download. 
So now we go back to our front end app, which is BackCountry Navigator for me. I've already placed my map on Smith Rock. As you can see there are no tracks or markers. Let's change that. 
In the map screen for BCN there is a hamburger menu in the top left. I click that which opens this menu. I select Trip Database. 
Now we select Import because we're importing the GPX that we exported from Caltopo. I didn't include screenshots of selecting the .gpx file. This will vary depending on device and it's simple enough to figure out. 
Now on the map screen we have our track and markers! This tells us what we need to download. On the top of this map screen is the Map Layers menu, represented by stacks of paper/maps. 
Inside the Map Layers menu there is a "Select Areas for Download" option. That's what we want. 
I select what I want to download and that's shown to me with the blue squares. There is one thing to remember when downloading from GIS sources: everything is downloaded by tiles. A tile is one square of the GIS grid. Everything is organized because of this grid. You can't download parts of tiles, generally. When downloading more is not always better. You'll see in the next step. 
Now we can jump back to our map screen. As you can see the map looks a bit different. This is because I'm in offline mode and it isn't showing data it doesn't have. But do you also see how it downloaded more than the blue squares? This is because of tiles. This means my blue download markers included partial tiles. Since we can't download partial tiles we have extra data. This usually doesn't make a huge difference, but it can, so be aware of it. 
And that's basically it. Every front end app is a bit different, so play around with it. Use your app for a lil while before relying on it. Never go out into nature without testing.
