If you think San Francisco is pretty now, wait till you see it in the future. Local architecture firm Iwamoto Scott proposes this curvy, colorful cityscape for the city by the bay, to accommodate a population that's slated to double by 2108. Some more details and pics after the jump.

Here are some of the proposal's highlights:

• An underground network of tunnels for hydrogen-powered hovercrafts.
• Highrises built on lowland buried by rising sea levels.
• A symbiotic, multi-scalar infrastructure for distributing and collecting basic needs like water, electricity, gas and consumer products, using aquifers and geothermal energy from the earth below San Francisco.
• Carbon nanotube walls built by drilling bots.
• A designated aquaculture zone with algae ponds, which doubles as raw material for hydrogen fuel production for distribution through those carbon nanotube walls.