The general scenario is set 80 or so years into the future, long after the sea levels have risen. The catastrophe side of the sea coming in has long since past and the five images are snapshots of people going about their lives, long since having adapted to the worlds new circumstance.
The scenes shown through light boxes present London as a tranquil utopia with the architecture of the distant rat race suspended below the water.
Think of "The World Without Us." Then imagine us still there.