Picture a dolphin diving toward the seafloor with something odd on its nose. It is not a shell or a fish. It is a sea sponge. The dolphin isn’t playing; it’s using the sponge as a diving mask: a clear ...

Tsukuba, Japan—The underwater dolphin kick is a swimming technique in which propulsion is generated solely through the undulatory motion of the lower limbs, increasing swimmers' speed by moving the ...