Send Bitcoin from Mainnet to Lightning Network & Back. Submarine swaps are atomic on-chain to off-chain swaps (and vice-versa) of cryptocurrencies. Conceptualized by Lightning Labs CTO Olaoluwa Osuntokun and Lightning Labs Infrastructure Lead Alex Bosworth, they are designed to facilitate the transfer from on-chain BTC to an off-chain Lightning Network (LN) channel. Currently, this is not directly possible without submarine swaps and requires an additional step where a user has to transfer LN funds to their on-chain Bitcoin wallet. Described as “on-chain ramps to the LN,” submarine swaps have several profound use cases and potential implications. Unlike atomic swaps — where LN needs to be enabled on both cryptocurrencies participating in an exchange — submarine swaps only need one side to be lightning enabled. As such, the future application of submarine swaps could see them becoming a vital infrastructure for decentralized exchange across various blockchains.