Six short lines, one sentence, and a single impossible wish: to speak in a way that works like seeing. The poem is a conditional. If light were a word, the speaker's tongue could turn into a glass-bottom boat, and he could "say and see / far into you." The central idea is a dream of language as a window, speech that doesn't just describe another person but lets us look into them. The poem also wants that looking to be gentle and unglaring, done "without being lit."
Its main image is a clever one. A glass-bottom boat is a vessel with a transparent hull, built so passengers can look down at what lives beneath them while staying on the surface, dry and safe. Making the tongue that boat joins two things we rarely connect. The tongue is the organ of speech, and here it also becomes an instrument of sight. The poem never mentions water, yet "glass-bottom boat" carries the whole sea with it. The reader supplies the depths, and that quietly turns "you" into something vast, dark and full of moving things. The phrase "far into you" lets the reader sink a little, as the speaker would.
The construction is spare. There is no rhyme, no punctuation and no capital letters, and the lines run only four to six syllables. The two tercets divide the work. The first sets up the hypothesis and the transformation, and the second delivers the result. The verb "could" appears twice, so the poem never leaves the realm of the possible. Nothing happens; something is imagined. The line break after "become" is a small piece of staging, because the word hangs in mid-air before "a glass-bottom boat" arrives, so the reader feels the change happen across the gap. "far into you" is the shortest line, a small drop in the poem's own depth.
Sound does quiet work too. In "glass-bottom boat" the blunt b's knock like a hull against a mooring, and the soft consonants of "glass" and the "say and see" pairing give the passage a hush. "Say" and "see" differ by almost nothing in sound, and that closeness mirrors the poem's wish that speaking and seeing could be nearly the same act.
The title adds a final turn. "Lit" is also the poem's last word, so the poem ends where it began, like a circle of light. The word has several possible meanings. The obvious one is "illuminated." The speaker wants to see without being lit, so he doesn't want to be spotlit or exposed, or perhaps he doesn't want to switch on a harsh external beam to do his looking. There is a paradox here, since the poem begins by imagining light as a word and ends by wishing to avoid being lit. One way to resolve it is to imagine the light passing through the speaker, as through the glass, without making him glow. Readers might also hear "lit" as slang for drunk, which would make the wish one for clear-eyed seeing, or as short for literature, which would make the poem a small comment on what words can do. The text doesn't force any of these, but it leaves room for them.
The poem balances closeness and distance. "far into you" suggests a longing for deep intimacy. A glass-bottom boat, however, keeps its passengers on the surface, separated from the water by a pane. The speaker would see a great deal but never get wet. Whether that is tenderness, caution or a touch of voyeurism is left open, and that openness is part of what makes the poem interesting.
Its significance lies in how much it gets out of so little. In six lines it builds a complete metaphor, tests it against a pun in the title, and ends with a question about how close we can really get to another person through words. It reminds us that a poem can be a tool as well as a statement, a small vessel that carries us out over something deep and lets us look down.