This secondary hydrogen gas explosion produces the visible flame above the bowl of water, lake or other body of water, not the initial reaction of the metal with water (which tends to happen mostly under water).
ðɪs sˈɛkəndɚɹi hˈaɪdɹədʒən ɡˈæs ɛksplˈoʊʒən pɹədˈuːsᵻz ðə vˈɪzᵻbəl flˈeɪm əbˌʌv ðə bˈoʊl ʌv wˈɔːɾɚ, lˈeɪk ɔːɹ ˈʌðɚ bˈɑːdi ʌv wˈɔːɾɚ, nˌɑːt ðɪ ɪnˈɪʃəl ɹɪˈækʃən ʌvðə mˈɛɾəl wɪð wˈɔːɾɚ wˌɪtʃ tˈɛndz tə hˈæpən mˈoʊstli ˌʌndɚ wˈɔːɾɚ.