This chapter examines the evolving security challenges facing critical maritime infrastructure in the North and Norwegian Seas amid Europe’s green energy transition. Against the backdrop of recent security incidents and geopolitical tensions, it analyses the interplay between environmental, economic, and security considerations in protecting vital offshore assets. The study explores the region’s diverse infrastructure landscape, including traditional oil and gas installations, expanding offshore wind farms, and extensive undersea cable networks. It addresses key challenges in infrastructure mapping, surveillance, and international cooperation while considering economic viability and investment concerns. The chapter highlights emerging best practices and emphasizes the need for adaptive security strategies that balance protection requirements with sustainable development goals. Drawing on recent events and policy developments, it argues for a comprehensive approach to maritime infrastructure security that encompasses military, cyber, and environmental dimensions while fostering effective public-private partnerships.