A raceway pond is a shallow artificial pond used in the cultivation of algae.[1][2]
The pond is divided into a rectangular grid, with each rectangle containing one channel in the shape of an oval, like an automotive raceway circuit. From above, many ponds look like a maze. Each rectangle contains a paddle wheel to make the water flow continuously around the circuit.
^Siva Kiran RR, Madhu GM*, Satyanarayana SV, Kalpana P, Bindiya P, Subba Rangaiah G. "Equilibrium and kinetic studies of lead biosorption by three Spirulina (Arthrospira) species in open raceway ponds." Journal of Biochemical Technology Vol. 6, no. 1 (2015): 894-909.