Ocean Controversy Grows As Pool "Censors" Whirlpool CoinJoin Transactions

Ocean's Bitcoin node software, developed by Luke Dash Jr, filters out certain types of transaction.

Is Bitcoin being co-opted by corporate and government interests?

Ocean, the Jack Dorsey-backed mining pool that recently raised $6 million in seed funding, has recently been criticized for filtering out Ordinals transactions, which its team describes as "spam".

Now, there are fresh accusations that Ocean is censoring Whirlpool CoinJoin transactions, notably implemented by Samourai Wallet and other privacy-focused services.

Ocean is known to run the Knots Bitcoin node software, developed by Bitcoin Core developer Luke Dash Jr, which includes the ability to block what he characterizes as spam transactions.

Is Knots The Ordinals Killer?
New Bitcoin software addresses the issue that critics call an ongoing “spam” attack on the blockchain.

What Is CoinJoin?

CoinJoin is a trustless method for combining multiple Bitcoin payments from multiple spenders into a single transaction. This makes it more difficult for outside observers to learn which spender paid which recipient(s) of the transaction.

One implementation of CoinJoin, Whirlpool, is used by the popular Samourai Wallet, and uses pools to enable rapid and efficient CoinJoins to enhance privacy.

In order to do this, Whirlpool transactions contain a little extra data within each Bitcoin transaction. 46 bytes are included in OP_RETURN, which marks a transaction as invalid and can be used to burn BTC or (controversially) store arbitrary data.

As in the case of Ordinals, the extension of the use of the Bitcoin blockchain beyond P2P cash appears to be what has turned Dash against Whirlpool. Knots limits the size of OP_RETURN to 42 bytes, meaning Whirlpool transactions are also effectively censored.

Growing Argument

Dash claims that this is a bug in Whirlpool, something hotly denied by Samourai.

As Samourai state, their wallet has been working since 2018 with no issue, since the standard Bitcoin software limits OP_RETURN to 80 bytes.

Dash/Samourai tweet screenshot
Samourai accuse Dash of lying.

Samourai goes further, accusing Dash of lying to the community by claiming his "niche fork" represents the norm. His motivation, they claim, is to censor "sinful" privacy-enhanced transactions.

Unfortunately we are not surprised as Luke has previously been caught censoring transactions and deploying blacklists for transactions he believes are sinful in the past.

Ultimately, Samourai claim, Ocean is an attempt by corporate interests, in collusion with state actors, to co-opt Bitcoin—taking it away from its cypherpunk roots and denying it its true role as peer-to-peer electronic cash.


Samourai say they are in negotiations with other miners to accept their transactions directly, avoiding using the mempool (the holding pen for transactions yet to be picked up by miners and confirmed).

They also say they have other strategies for addressing the problem, should pools other than Ocean adopt the same approach of censorship.

They finish their thread with a call to action, asking miners to point their hashrate at different pools, to send a strong message that censorship is not acceptable.

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