To provide a culture system, a culture facility, and a culture method of seafood capable of significantly reducing initial cost of installation of facility equipment and running cost of an operation of the facility equipment, by using a semi-closed circulation type water tank which uses underground sea water for a heat source and water quality purification.SOLUTION: A culture system 1 comprises: a culture facility 2 in which, a heat insulation side groove 22 is provided in a circumferential direction on a floor face 212 and a closed space is formed； a water tank part 3 installed in the facility 2； and a supply hole 4 for withdrawing underground sea water from an underground constant temperature layer U and supplying the underground sea water to the water tank part 3. The culture system further comprises: a discharge part 32 for discharging some of culture water which overflows out of the underground sea water supplied to the water tank part 3 to the heat insulation side groove 22. The culture water discharged from the discharge part 32 flows as a straightening flow which is lifted up/down and agitated inside of the heat insulation side groove 22. At the time, heat from an external part is heat insulated by the straightening flow which is lifted up/down and agitated of the underground sea water in the heat insulation side groove 22, so that, a temperature of the culture facility 2 is kept to a temperature of the underground sea water always.SELECTED DRAWING: Figure 1【課題】地下海水を熱源と水質浄化に利用する半閉鎖循環式水槽を用いて、施設設備設置のイニシャルコスト、及び施設設備運転のランニングコストを大幅に低減することができる魚介類の養殖システム、魚介類の養殖施設、及び魚介類の養殖方法を提供することを目的とする。【解決手段】養殖システム１は、床面２１２に断熱側溝２２が周設され閉空間が形成された養殖施設２、養殖施設２内に設置された水槽部３、地下恒温層Ｕから地下海水を揚水して水槽部３に対して供給する供給部４を備えている。水槽部３に供給された地下海水のうちオーバーフローした飼育水の一部が断熱側溝２２に放出される放出部３２を有している。放出部３２から放出された飼育水は、断熱側溝２２内を昇降撹拌する整流として流れる。このとき、外部からの熱は断熱側溝２２内の地下海水の昇降撹拌する整流により断熱されるため、養殖施設２は常に地下海水の温度に保たれる。【選択図】図１
