ɐ stɹˈɛtʃ ʌvðə tˈiːsnˈɑː fˈɔːɹmz ɐ bˈoːɹdɚ bᵻtwˌiːn kˌʌvʃɪnˈɑːvski ænd ˌɑːstɐʃkˈɑːvski dˈɪstɹɪkts, ænd ɐ ʃˈɔːɹt stɹˈɛtʃ nˈɔːɹθ ʌvðə fˈɜːst wˈʌn fˈɔːɹmz ðə bˈoːɹdɚ bᵻtwˌiːn kˌʌvʃɪnˈɑːvski ænd fɪɹˈɑːvski dˈɪstɹɪkts.
A stretch of the Tsna forms a border between Kuvshinovsky and Ostashkovsky Districts, and a short stretch north of the first one forms the border between Kuvshinovsky and Firovsky Districts.