In recent years, strong concerns have been raised over the increasing numbers of disorderly protests and aggressive activism at sea. Maritime protests raise difficult – and understudied – legal questions concerning the boundaries between the legitimate application of rights of freedom of speech and assembly on the one hand, and the need to ensure safety of navigation on the other. This article examines the legal arguments in favour of maritime protest as well as national responses to it, in the context of two Polar case studies. Firstly, this article appraises the confrontational activism of the Sea Shepherd Conservation Society in its anti-whaling campaign in Antarctica, and the problematic application of anti-piracy legislation to more aggressive campaign groups. Secondly, this article examines the position in relation to oil platforms, as exemplified by the Prirazlomnaya dispute in the Arctic, as well as controversial developments in Antarctic jurisdictions. In so doing, this article argues that the protection accorded to direct action protests at sea is considerably more limited than many campaign groups might appreciate.