It's not the most economically valuable issue in EU-Britain divorce talks
But access to British waters and stable fishing quotas are among the most politically sensitive.
So too is the half a trillion euros worth of annual trade at stake as Britain and the EU head back into talks Monday (March 2).
They're hoping to thrash out how their relationship will look after Brexit.
Both say they want to reach a deal by the end of the year.
That would allow solutions to contentious issues from aviation to fisheries to kick in from 2021.
The EU wants give Britain access to its single market of 450 million people in exchange for solid guarantees that London would prevent dumping.
But Boris Johnson has said he wants to move away from the EU.
And refuses to be bound by its rules or the jurisdiction of its top court.
He's already upset the bloc by backpedalling on issues agreed in their divorce package last year.
Britain and the EU will assess in June whether sealing a basic trade deal is possible by the end of the year.
Without one, trade volumes could shrink dramatically.
The lack of trust between the EU and Britain has been exacerbated by comments from London that it might not carry out border controls on the sensitive Irish frontier... the most fraught issue in the talks.