The speaker is mourning a lover who has left, and the title casts him as Balboa, the explorer who "discovered" the Pacific. He has gone off to find something new, while she stays behind with the aftermath. Her tone shifts between brisk, almost polite farewells ("bon voyage," "wishing you courage") and raw physical memory. She recalls the last night, the moon over the water, his bones and muscles moving over her, and she can still feel his back under her hand.
The poem suggests that words failed them. She repeats "After the words," as if talking only caused damage, and she mentions repairing her lips "from their blood." What remains is the body and the silence that once joined them, which she says had "no errors."
The mood is wistful and bittersweet. Her good wishes sound generous, but the ending, "where you go / without me," shows how much the loss still hurts.