This past September, tourists and locals alike were surprised to see a hippo lazily floating down the Thames River in London. Dutch artist Florentijn Hofman created the unusual artwork, called HippopoThames. The 69-foot-long sculpture is made of overlapping wood panels and features large, cartoon-like eyes and a pink nose and ears. Built over a small boat, HippopoThames is half-submerged in the water, so it moves like a real hippo bobbing with the tide.

Hofman created the playful piece for a citywide arts festival celebrating the Thames. When researching the history of the area, the artist discovered that hippos inhabited the river in prehistoric times. Hofman, who is known for his supersized public art installations, says, “the purpose of setting my sculptures in the public domain has always been . . . to inspire conversation and to cause astonishment.”