One of the four situations that require one to recite Birkat Ha’gomel upon emerging safely is "Yoredeh Ha’yam" – one who traveled in the sea. Sea travel is regarded as a dangerous situation, and thus after emerging safely from a sea voyage one is required to recite Birkat Ha’gomel.
The question arises whether this includes a cruise on a relatively safe body of water, such as a lake. For example, if people take a cruise on the Kinneret lake in northern Israel, must they recite Birkat Ha’gomel afterward?
Hacham Ovadia Yosef addresses this question in Hazon Ovadia – Hilchot Berachot (p. 363; listen to audio recording for precise citation), where he writes that even after a cruise in the Kinneret, one must recite Birkat Ha’gomel. As Hacham Ovadia notes, even sailing in a lake can pose a risk, and indeed, there are reported tragedies that have, unfortunately, occurred in the Kinneret. Sailing in the Kinneret is thus no different from sailing in other bodies of water in this regard, and obligates one to recite Birkat Ha’gomel. Hacham Ovadia adds that this applies even if the boat sailed near the shoreline and a lifeguard was present on the boat. For that matter, anytime one takes a trip by boat or yacht for several hours, not to mention for several days, he must recite Birkat Ha’gomel after the trip.
Summary: One must recite Birkat Ha’gomel after sailing at sea in a boat or yacht, even if one sails on a lake such as the Kinneret.