One of the situations requiring the recitation of Birkat Ha’gomel is a journey in the ocean. The chapter of Tehillim which discusses the obligation of Birkat Ha’gomel describes the situation of "Yoredeh Ha’yam Ba’oniyot Oseh Melacha Be’mayim Rabim" ("Those who descend into the ocean in ships; who do their work in the high seas" – Tehillim 107:23). One who travels in the sea by ship for a period of seventy-two minutes or more, roundtrip, recites Birkat Ha’gomel after the trip.
There is a debate among the Halachic authorities as to how this Halacha applies nowadays. Ashkenazic authorities rule that since modern technology has made it much safer to travel in the sea, one does not recite Birkat Ha’gomel after traveling by boat, unless he took a several-day journey in the high seas. This is the ruling of Rav Moshe Feinstein (Russia-New York, 1895-1986), in his work Iggerot Moshe (Orah Haim, 2:59), and of Rav Eliezer Waldenberg (Israel, 1915-2006), in his Sitz Eliezer.
Sephardic authorities, however, maintain that even nowadays, one must recite Birkat Ha’gomel after a boat trip, because despite technological advances, accidents still occur at sea, Heaven forbid. As long as the trip lasted a total of seventy-two minutes or longer, and the boat went far enough out to sea that it was not visible at the shore, the traveler must recite Birkat Ha’gomel. Thus, for example, if somebody goes deep sea fishing, or on a party boat that sails in the ocean far away from the shore, and the trip lasts at least seventy-two minutes, he must recite Birkat Ha’gomel after the trip. It makes no difference whether the trip was taken for professional purposes (as in the case of a professional fisherman) or for recreation. In either case, one must recite Birkat Ha’gomel after the trip. This is the ruling of Rav Shemuel Pinhasi (contemporary), in his work Ve’chol Ha’haim (p. 48; listen to audio recording for precise citation).
Summary: According to Sephardic practice, if one goes on a boat trip in the ocean that lasts at least seventy-two minutes, and the boat sails deep enough into the sea that it is not visible from the shore, he recites Birkat Ha’gomel after his trip.
