In order to make payments on the lightning network — Bitcoin’s second layer solution for instant and cheap transactions — users must first fund lightning channels. This process, however, creates a slight disconnect between lightning users and on-chain users. Lightning users can pay lightning users, and on-chain users can pay on-chain users, but they can’t pay one another directly.
To solve this, “Submarine Swaps” allow users to make trustless transactions between lightning addresses and on-chain addresses in either direction. The technology could be a game changer for both Bitcoin lightning and mainnet users, as it would remove the transaction barriers between them.