Task: Translation
Input (Japanese): 正確な原因は不明だが、目撃者によると、波を受けた船が突然左に傾き、乗客は船の片側に倒れて行ったとの示唆もある。
Output (English): The exact cause is unknown - suggestions from eyewitnesses include the boat suddenly turning left, being hit by a wave, and many of the passengers moving to one side of the boat together.