This is what I did with my evening. To be precise, I had a small part in creating the conditions that made this possible. We did not execute perfectly for various and sundry reasons, but that’s what the human ability to learn and improve is for.
For non-Ingress players: the primary means of scoring points in the game is creating fields. Bigger fields are more points. Fields are always triangles. You create fields by generating links between portals. You make a link between two portals by going to the source portal and using up a key to the destination portal.
Thus, you could make a big triangle like that by creating a link between a portal in Oakland and a portal in Marin Highlands; then between the same portal in Oakland and a portal in Half Moon Bay; and then between the Half Moon Bay and Marin portals. Boom, lots of green.
Oh, yeah. The tricky part is that links can’t cross. So if there was already a link between, say, Candlestick Park and Alameda, you couldn’t create the link between Oakland and Half Moon Bay. This makes life tricky.
The coordination aspect of this is really the fun part, particularly since the other team will try and stop you from scoring via various methods if they notice. It’s like a much lower pressure version of moving your servers between data centers: plenty of planning, lots of moving parts, and a good team of people.