The speaker celebrates a loving relationship that has felt secure and supportive. The couple has faced difficulties together, and the speaker values the comfort and strength they receive from their partner. The repeated plea not to disturb things suggests a sudden worry: perhaps the partner is considering a change that could upset their shared stability.
The central image compares love to a ship at sea. Their journey has included storms, but they have stayed afloat, carrying a “cargo” of love and devotion. A “quiet place to harbor” suggests a safe refuge they make for each other. “Rock the boat” means to disrupt a settled situation; here, the phrase also fits the sailing image, making the warning feel both playful and anxious.
The song can be heard as a warm request to protect a good relationship, but the repeated question—where the partner got the idea to rock the boat—leaves some uncertainty about what has happened. The speaker may simply be teasing, or may fear that the partner is about to change their relationship. The lyrics do not explain the cause, so the tone sits between affectionate confidence and concern.