lightning-submarine-swapsSubmarine swaps: atomic on-chain ↔ Lightning conversions via shared HTLC preimage. Boltz protocol, Loop protocol, Peerswap (P2P), trustless variants with adaptor signatures. Boltz swaps are offline (suspended 2026-08-03); Loop, Peerswap and Blockstream Swaps (beta) are the live options as of September 2026. USE WHEN: building swap services, integrating with…
Independent GitHub snapshot · Automated classification · Original documentation governs
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.
Both sides commit to same hash H = SHA256(P) (or scalar T = t*G for PTLC).
Side 1 claims: requires P (or t).
Side 2 claims: refundable after timeout, or claimable with P (or t).
Whoever moves first reveals P → other side can immediately claim.
Either both legs settle, or both refund.
| Service | Status as of 2026-09-15 | Notes |
|---|---|---|
| Boltz | Offline since 2026-08-03 | All mainchain, Lightning and Liquid swaps disabled "until further notice"; EVM-side swaps (USDT, USDC, TBTC, WBTC, RBTC) went first, on 2026-08-01. |
| Loop (Lightning Labs) | Operating | lightninglabs/loop v0.35.0-beta, released 2026-08-25. |
| Peerswap | Operating, Bitcoin only | v7.0.1 (2026-09-07) rejects new L-BTC swap requests in both directions after a Liquid Network security incident; Bitcoin swaps unchanged. |
| Blockstream Swaps | Beta since 2026-08-10 | In-house swaps feature for the Lightning and Liquid networks; beta testing with select participants, access by request. |
Boltz cited months of "automated, AI-assisted probing" of its infrastructure and several exploits: attackers "iterate faster than a team our size can find and patch". Because the swap design is non-custodial, user funds were never at risk — Boltz absorbed the losses on its own liquidity, the refund API stayed up, and unilateral refunds never depended on Boltz infrastructure at all. On 2026-08-12 all three founders announced their departure, handing the project to an undisclosed group of Bitcoiners supplying capital and engineering; no relaunch date had been announced as of 2026-09-15.
Downstream integrators that lost swap functionality: ZEUS, Aqua (JAN3), Bull Bitcoin.
Practical consequence: the Boltz sections below stay as a protocol reference — the flows and script templates are unaffected by the outage — but do not plan a new integration against the live Boltz API until the service returns.
Boltz was the most widely integrated swap service until its 2026-08-03 suspension (see status above). Two flow types:
1. User generates preimage P, sends LN payment with H = SHA256(P) to
Boltz.
2. Boltz holds the LN HTLC.
3. Boltz publishes on-chain HTLC at user's address, value =
payment_amt - fee.
4. User claims on-chain HTLC by revealing P.
5. Boltz uses P to fulfill the LN HTLC.
1. User publishes on-chain HTLC paying Boltz (value = lightning_amt + fee).
2. Boltz pays user's LN invoice (which has H = SHA256(P)).
3. User claims their own LN payment with P.
4. Boltz uses P to claim the on-chain HTLC.
Boltz API: REST endpoints for quotes + swap construction (v2 current, v1 deprecated; docs at api.docs.boltz.exchange). Swap creation has been disabled since 2026-08-03.
Boltz / Loop are "service" submarine swaps — you trust the service to act honestly within the timeout window.
Trustless / scriptless variants use adaptor signatures:
PTLC-based swaps (Schnorr point-locked, BOLT proposal):
t unlocks both.Peerswap enables direct peer-to-peer swaps without 3rd party:
CLN plugin and LND-via-lncli plugin available. Swaps are only allowed with allowlisted peers, and the project still labels itself beta-grade.
As of Peerswap v7.0.1 (2026-09-07) new L-BTC swap requests are rejected in both directions — local RPC and incoming peer requests alike, and L-BTC is dropped from capability announcements — following a Liquid Network security incident. Bitcoin swaps are unchanged. Recovery of already-persisted Liquid swaps stays enabled but is not guaranteed.
Offline along with the rest of the service as of 2026-09-15; listed here because they define the feature surface a returning Boltz (or a replacement) is expected to cover.