And inside, a portal to the water dimension.

Finally, another portal from the fire dimension to the mortal realm.

Water turns to steam inside the fire dimension creating an insulation layer of steam and a layer of water between the two fire dimension X mortal realm portals. Sandwich of chicago-portal->water->latvia-portal. Boom, cheaper than air travel.

Water gets hotquickly still, so you only keep it all together for a small period of time, but jump through and you're a steaming wizard coming out of a portal wherever you want