How do those who travel by ship perform their prayers?

On means of transport such as ships, where it is possible to stand upright, the essential rule is to perform the prayer standing, facing the qibla, and carrying out the bowing (ruku) and prostration (sujud) as usual. If it is not possible to pray standing due to reasons such as dizziness, one may pray sitting on the ship; and if possible, the prayer should still be performed with bowing and prostration rather than by mere gestures. At the beginning of the prayer, one should face the qibla if possible, and as the ship changes direction, the person should also turn towards the qibla. Unlike riding animals, it is also permissible to perform congregational prayer on a ship (Kâsânî, Bedâi‘, 1/109-110).

Source: T.C. Diyanet İşleri Başkanlığı, Din İşleri Yüksek Kurulu