Submarine Swaps A submarine swap atomically converts between on-chain BTC and Lightning BTC (or vice versa) using a single shared preimage that reveals one side, allowing the other side to claim. Atomicity primitive Boltz protocol Boltz is the most popular swap service. Two flow types: Boltz Reverse (LN → on-chain) Boltz Submarine (on-chain → LN) Boltz API: REST endpoints for quotes + swap construction. Trustless variants (adaptor signatures) Boltz / Loop are "service" submarine swaps — you trust the service to act honestly within the timeout window. Trustless / scriptless variants use adapto…