Part of the 14 Cities series:

"As the Gold Coast’s canals finally began to disappear beneath the waters of the rising Pacific in May 2041, it became embarrassingly clear that the Gold Coast Development Corporation was faced with a stark choice: retreat or adapt.

Whilst a few die-hard Gold Coast dwellers decided to construct small floating harbours of pontoons, lashed together and floating sentimentally above their former properties, a more expansive development began to emerge around the partly submerged towers on the coast.

After the towers had been sealed, each became the pinion in a large circular partially-algal platform structure floating on the clear blue water. This structure is inhabitable above water and rapidly growing beneath, as chemically-controlled beneficial blooms naturally cleanse the effluent and exhaust from the constant small boat traffic, reduces ambient temperature, and generates cheap energy transforming CO2 into lipids (oils). The increasingly intense heat above the water causes other varieties of megaflora to emerge, creating rippling tropical forests around the circular platforms laced through the towers.

Underwater, the lower floors of the old towers contain glass-lined hotel rooms with views onto the new reef of a turqoise drowned world of Karl Langer hotels and barnacled neon silhouette signs. Algalia’s economy is in both tourism and algae-derived oil exports."

Notes: Echoes of JG Ballard's The Drowned World here (megaflora etc.) of course, which I've previously referenced with respect to Australia, and Queensland in particular, though the pontoons are also a nod to elements Constant's New Babylon to some degree (although that's as far from this as is possible, politically), as well as to traditional floating harbours. See also the debates over 'planned retreat' around many Australian coastlines. The potential of algae is being looked at from numerous angles, as many of you will know.