Jeff Lindsay notes that the name "Irreantum," said to mean many waters (1 Nephi 17:5), was what the Nephites called the ocean when they arrived at the shores of southeastern Arabia. Rabbi Yosef ben Yehuda, a non-LDS author of the former Jewishness of the Book of Mormon Website, suggests in an e-mail from Dec. 1997 that Irreantum may be derived from Egyptian:
Ir (river re (mouth na (many) tehem (water)
If so, it sounds like a great name to give to the ocean while standing in a wadi where a large fresh water lagoon and a seasonal river meets the sea. [jefflindsay.com/BMEvidences.shtml]
“And We Beheld the Sea Which We Called Irreantum”
When Lehi's party finally arrived at Bountiful, they "beheld the sea, which [they] called Irreantum, which, being interpreted, is many waters" (1 Nephi 17:5). The Prophet Joseph Smith explained that "Lehi went down by the Red Sea to the great Southern Ocean, and crossed over to this land," meaning America (Teachings of the Prophet Joseph Smith, 267). According to the Hiltons, what would the "great Southern Ocean" have been but the Arabian Sea and Indian Ocean to the south of Arabia? . . . The Greeks of the first century A.D. called this sea "Erythraem." The similarities between the Greek name (Erythraem) and Nephi's term (Irreantum) is astonishing:
IR--RE--ANT--UM
ER--[R]Y--THRA--EM
[Lynn M. and Hope A. Hilton, Discovering Lehi, p. 21]