Geopointe

How can I access all the records I have at one location on the map?

By default, hovering over a marker at a location with multiple records will alert you how many are at that location.

Same-Location-Marker-A

Alternatively, you could make it immediately visible with a Same Location Marker:

Same-Location-Marker-B

No matter which you choose, when clicked, you see the names of all the records at that location.

Same-Location-Marker-C

Clicking on a name will bring up their info window, just like any other record.

How do I turn on Same Location Markers?

Individual settings can be changed by clicking the Gear icon located in the upper right corner of the map and selecting On or Off next to Same Location Markers

Geopointe Admins: You can set the default for your company in the Org Settings tab of Geopointe Setup. Just be aware that any user can override this with the steps above. 

In Mobile

Same Location markers don't appear in Salesforce mobile, but you can see all the records at a location by tapping the marker, as demonstrated in this document: View Overlapping Records in Salesforce Mobile