Hazrat Ka'b al-Ahbar (may Allah have mercy on him) says: "When a person boards a boat, all his past sins are forgiven as if he were born from his mother's womb, and the one who drowns in the sea is like a martyr drenched in blood, and the one who is patient is as if he has a royal crown on his head."
Hadith Referenceسنن سعید بن منصور / كتاب الجهاد / 3576