Olympic divers wonder why their pool is green

The water of the diving pool at right appears a murky green, in stark contrast to the pool's previous day's color and also that of the clear blue water in the second pool for water polo at the venue as divers train in the Maria Lenk Aquatic Center at the 2016 Summer Olympics in Rio de Janeiro, Brazil, Tuesday, Aug. 9, 2016. (AP Photo/Matt Dunham)

Combined ShapeCaption
The water of the diving pool at right appears a murky green, in stark contrast to the pool's previous day's color and also that of the clear blue water in the second pool for water polo at the venue as divers train in the Maria Lenk Aquatic Center at the 2016 Summer Olympics in Rio de Janeiro, Brazil, Tuesday, Aug. 9, 2016. (AP Photo/Matt Dunham)

Before the Olympics, fans were worried about the state of the waters surrounding Rio de Janeiro. Now, the Olympics are here and everyone is wondering what happened to the water in the diving pool.

Diving fans were dismayed to see that the water's blue hues from the first few days of competition were gone, replaced by a green, murky pool.

British synchronized diver Tonia Couch said the water made it impossible for her to see her partner.

The leading theory about the color change is that an algae bloom started because the pool didn't have enough chlorine.

Sports Illustrated noted that algae typically blooms in warmer water, which could explain why the warmer waters under the diving platforms turned green, while the cooler swimming pool is still blue.

A spokesman for the games said officials are investigating the cause and added that they did test to make sure the water was safe for competitors.

This video includes images from Getty Images.