Welcome to Explorer! To get started with the app, you'll open a map and learn how to navigate and work with it using map tools as you explore volcanoes and the risk of lava flow on the island of Hawaii.
Note:
If you've completed the Get Started with Map Viewer Learn lesson, this will seem familiar. You are doing many of the same things you did in Explore a map but using Explorer instead of a browser. Return to that lesson to learn how to create the map.
Install and open Explorer
Install ArcGIS Explorer from the App Store if you don't already have it on your device. Start the app. You can sign in to your ArcGIS account or use the app without signing in.
Without signing in, you can view sample maps and search for public maps on ArcGIS Online.
If you've never opened a map in the app, you'll see the Maps list, where you explore and find maps. If you were already signed in and you have previously opened a map in the app, you'll see your previous map. If it isn't the Hawaii Island Lava Flow map you'll use here, tap Maps.
Find and open the map
You'll use the Hawaii Island Lava Flow map to become familiar with Explorer. If you are not signed in, you'll see this map in the Sample Maps category. Otherwise, search for it in the Maps list. Tap the Hawaii Island Lava Flow Risk map to open it.
The map opens to show the island of Hawaii. Instead of beaches and greenery, you see a geologic classification of the island into lava flow hazard zones of different severity. The map also shows volcanoes, emergency shelters, and highways.
Tip:
Explorer supports opening a link to a specific map, and that link can be used to make a QR code that launches the app. Another way to open the map for this lesson is to scan this code, which opens the Hawaii Island Lava Flow map in Explorer:
Explore the map
The map contains layers, and layers contain features. For example, each volcano is a feature in the Volcanoes layer. In this section, you'll get information about the features and navigate the map.
Tap a volcano on the map, such as Mauna Loa.
Tapping it shows all the features at its location. For Mauna Loa, there is the volcano itself and one or more lava flow hazard zones.
From the list of features, tap the volcano to select it.
Information about Mauna Loa displays in the panel. This is called the feature's pop-up. Mauna Loa, which last erupted in 1984, is one of three active volcanoes on the island. Mauna Kea is extinct.
Tap the volcano's Media tab to see images associated with the volcano.
Tap the image of the volcano and tap Open Link to open a large, captioned version of the image in the browser.
Close the browser tab with the detailed image. Tap Back to Explorer (iOS 9) or Explorer (iOS 10 or later) in the upper left corner to return to the app.
Close the pop-up and close the list of features at the volcano's location.
Tap Overflow and use Bookmarks to return to the default extent of the map.
Tap a lava flow hazard zone, for example, the Kohala Coast, the red area around Hualalai.
Similar to when you tapped the volcano, you may see multiple features at this location. If so, tap the hazard area you are interested in.
Tip:
If you aren't sure which areas are lava flow hazard zones, turn other layers in the map off to focus on the zones. Use Layers to turn off the other layers.
Similar to when you selected Mauna Loa, you see information about the hazard zone. You can view its media to see images, and tap those images to see additional information about them.
Tap the red square in the panel, which is the symbol used for the Kohala Coast, to zoom to that feature.
Close the hazard zone pop-up, and close the list of features if there is one.
On your own, learn more about the volcanoes, hazard zones, and emergency shelters on the map. Pinch and stretch with two fingers to zoom in and out on the map.
When you're finished, use Bookmarks to return to a full view of the island. Close Bookmarks.
View the map contents
To work directly with the map layers, you'll use Layers.
Tap Layers to see the contents of the map.
The order of the layers in the Layers list is the order in which they are drawn on the map. Every layer can be turned on and off.
Tip:
Explorer presents the basemap layer separately; you can't turn that layer on and off, but you can view it and change it using another tool. You'll do so later in this exploration. Explorer also adds a layer that isn't part of the original map: Markup. You'll learn more about it in the next section.
Use the Lava Flow Hazard Zones toggle button to turn the layer off.
You see the Terrain layer underneath. The Terrain layer was already partially visible because of a transparency setting on the Lava Flow Hazard Zones layer, but now it is more clear.
Turn off the Terrain layer to see the Topographic basemap.
Turn the Lava Flow Hazard Zones and Terrain layers back on.
Close the Layers list.
Use map tools
You can also work with the map using tools on the toolbar.
On the toolbar, tap Overflow and tap Measure in the menu.
The toolbar shows the measure tools, with Measure Distance selected.
Zoom in on the island to make better use of the space on the screen.
On the map, tap Mauna Loa to start a measurement.
Tap another volcano, such as Hualalai, to measure between the two volcanoes.
Make a few more measurements. You can continue the one you've started and measure between multiple volcanoes, or use Discard to clear your measurement and start again. When you're finished, tap Done.
On the toolbar, tap Overflow and tap Basemap to open the Basemap gallery. Tap Oceans or another basemap.
Note:
The basemaps you see might differ, as Explorer honors the basemap gallery of your organization.
The new basemap is shown.
Change the basemap back to the default (Topographic) basemap.
Tap Markup.
You'll circle Mauna Kea on the map.
Use your finger to draw a circle around the volcano.
Tap the circle in the pop-up to clean up your drawing, making your sketch into a perfect circle.
Note:
For the pop-up to appear, the shape you drew has to be close to a circle.
A circle appears around Mauna Kea.
Tap Color and change the color of your circle to green.
Your markup is now green.
Tip:
This was a short introduction to markup. To learn more, see Markup.
Tap GPS to center the map on your location. If prompted to allow Explorer to access your location, tap Allow.
Next steps
You should now be familiar with the app. Think about how your organization can use Explorer.
and use Bookmarks 
to return to the default extent of the map.
to turn off the other layers.
in the menu.
selected.
to clear your measurement and start again. When you're finished, tap Done. 
to open the Basemap gallery. Tap Oceans or another basemap.
.
to center the map on your location. If prompted to allow Explorer to access your location, tap Allow.