温海 is read as あつみ (atsumi) and means warm sea.
あつみ
atsumi
かいようおんどさはつでん
ocean thermal energy conversion
かいすいおん
seawater temperature
あたたまる
to warm oneself
あたたかい
having enough money
あたためる
to renew (an old friendship)
おんわ
moderate (statement, measure, etc.)
おんど
temperature
おんしつ
greenhouse
おんせん
hot spring
おんたい
temperate zone
ぬくい
warm
ぬるい
lenient