Exodus 20:11 (King James Bible) for in six days the LORD made heaven and earth the sea and all that in them is
The Book of Mormon text has an and before the sea, with the result that the conjoined structure is fully coordinated (“heaven and earth and the sea and all that in them is”). The ancient versions (Greek, Syriac, Latin, the Targums, and even many Hebrew manuscripts) also have the and before the sea, so the Book of Mormon text here either fulfills a natural tendency to add the and or represents the Hebrew original text (which would imply that what became the standard Masoretic Hebrew text for Exodus 20:11 accidentally lost the prefixal and at some earlier time).
Summary: Retain in Mosiah 13:19 the highly expected and before the sea; other ancient versions strongly support the and here in this quotation of Exodus 20:11.