æt lˈiːst ɐ pˈoːɹʃən ʌvðə kˈeɪv mˈʌstɐv ɐ tˈɛmpɹɪtʃɚ bᵻlˌoʊ zˈiəɹoʊ dᵻɡɹˈiːz sˈiː θˈɜːɾi tˈuː dᵻɡɹˈiːz ˈɛf ˈɔːl jˈɪɹ ɹˈaʊnd, ænd wˈɔːɾɚ mˈʌstɐv tɹˈævəld ˌɪntʊ ðə kˈeɪvz kˈoʊld zˈoʊn.
At least a portion of the cave must have a temperature below 0 °C (32 °F) all year round, and water must have traveled into the cave’s cold zone.