Where is the hot water sea in this world?

Red Sea - It is an extension of Indian Ocean and Located between Africa and Asia.

It's water is hot because of Hot sunny days,Absence of rainfall, desert dust storms,high levels of evaporation etc.

Red Sea

Hot water sea is on the east coast of the Coromandel Peninsula, Newzealand.

 

I am not sure if its called as Hot water sea but the Red sea is indeed warmer in its depth than on the surface. For more details see the link

http://www.divediscover.whoi.edu/ventcd/vent_discovery/earlyclues/evidence_redsea.html

I am also requesting you to please not create questions for which you easily get answers upon Googling.