With this plugin you can plan a route with multiple portals and open Google Maps to start your navigation.
Start by selecting your first destination portal. Click the 
on the control buttons toolbar. A route marker will be drawn.
Select your next destination portal and click the button again. A route will be drawn.
Click the 
button to remove a selected waypoint.
Continue with more portals, up to 9 portals.
Click on the 
Maps marker to open the route in Maps
From the 
menu you can edit the waypoints list. You can move waypoints up or down, or delete a single waypoint. You can also clear all waypoints.
You can also share the Maps URL to share or store for later use.
From the edit menu you can change the order of waypoints (move up/down) or delete a single waypoint.
You can also reverse the order of waypoints.
Every edit will immediately be drawn on the map.
There are several transfer options from the plugin transfer menu:
With Google Maps you can create a route with a maximum of 9 waypoints.
Start with this url, containing api=1: https://www.google.com/maps/dir/?api=1
The route always starts with 1 destination: https://www.google.com/maps/dir/?api=1&destination=lat,lng (replace lat,lng with 2 floating point values, latitude,longitude)
Every next waypoint (lat,lng) can be added as a range of waypoints, joined by pipe (|)
waypoints=lat,lng|lat,lng|lat,lng
where every comma (,) is replace by %2C and every pipe (|) is replace by %7C:
https://www.google.com/maps/dir/?api=1&destination=lat,lng&waypoints=lat%2Clng%7Clat%2Clng%7Clat%2Clng
By default a route starts from your location.
As an option you can also show a preview route by adding an origin which will be used as the starting location:
https://www.google.com/maps/dir/?api=1&destination=lat,lng&origin=lat,lng&waypoints=lat%2Clng%7Clat%2Clng%7Clat%2Clng
You can also choose a travelmode:
https://www.google.com/maps/dir/?api=1&destination=lat,lng&origin=lat,lng&travelmode=driving&waypoints=lat%2Clng%7Clat%2Clng%7Clat%2Clng
Source: https://developers.google.com/maps/documentation/urls/get-started