Underwater Treadmill Dog

underwater
Underwater is a term describing the realm below the surface of water where the water exists in a natural feature (called a body of water) such as an ocean, sea, lake, pond, or river. Three quarters of the planet Earth is covered by water.
Situated, occurring, or done beneath the surface of the water
submerged: beneath the surface of the water; "submerged rocks"
subaqueous: growing or remaining under water; "viewing subaqueous fauna from a glass-bottomed boat"; "submerged leaves"

treadmill
a job involving drudgery and confinement
An exercise machine, typically with a continuous belt, that allows one to walk or run in place
an exercise device consisting of an endless belt on which a person can walk or jog without changing place
a mill that is powered by men or animals walking on a circular belt or climbing steps
A device formerly used for driving machinery, consisting of a large wheel with steps fitted into its inner surface. It was turned by the weight of people or animals treading the steps
A job or situation that is tiring, boring, or unpleasant and from which it is hard to escape

dog
A domesticated carnivorous mammal that typically has a long snout, an acute sense of smell, and a barking, howling, or whining voice. It is widely kept as a pet or for work or field sports
A wild animal of the dog family
The male of an animal of the dog family, or of some other mammals such as the otter
a member of the genus Canis (probably descended from the common wolf) that has been domesticated by man since prehistoric times; occurs in many breeds; "the dog barked all night"
chase: go after with the intent to catch; "The policeman chased the mugger down the alley"; "the dog chased the rabbit"
frump: a dull unattractive unpleasant girl or woman; "she got a reputation as a frump"; "she's a real dog"