Provided is a float structure (100) that comprises the following: an upstream flow path (70) in which seawater which flowed in from a seawater inlet (10) flows; a downstream flow path (80) in which the seawater which flowed in from the upstream flow path (70) flows and is guided to a seawater outlet (20); a linking flow path (90) that links the upstream flow path (70) and the downstream flow path (80); and a heat exchanger (30) provided to the linking flow path (90) and for cooling a heat source of plant facilities by using seawater. The heat exchanger (30) is provided forward from an in-flow position at which seawater flows in from the upstream flow path (70) to the linking flow path (90) and rearward from an out-flow position at which the seawater flows out from the linking flow path (90) to the downstream flow path (80).
