This is Lake Elementeita in the Great Rift Valley in Kenya. Much of this lake lies within the 48,000 acre Soysambu Conservancy, of which more another day.
It is a soda lake, only about 1 meter deep. These alkaline lakes arise when there is little outflow from the lake, and the water becomes saline and has very high levels of dissolved carbon dioxide. As a result, these hostile-seeming environments are in fact very rich ecosystems, full of algae and bacteria such as cyanobacteria, a favorite food of the flamingo.
These lakes also often host brine shrimp, which the flamingoes love and which turn their feathers pink.
These are Greater Flamingoes, Phoenicopterus rose; their bill is mainly pink, not black, unlike the rarer Lesser Flamingo:
The largest males can be up to six feet tall. They stir up the mud with their feet, and then filter out the shrimp, algae, and small crustaceans with their head famously upside down.* Their upper jaw is movable, which helps!
The same lake hosts other waterfowl, like this yellow-billed stork:
And this Cape Teal duck:
* Even with their heads down, flamingoes are not well-suited to croquet, as Alice discovered: