If the Sea Peoples never disappeared, how could Britain later take control of the oceans from them?
Short answerIt might never do so, because a continuous Sea Peoples state would enter the modern era with an overwhelming head start in trade, institutions, and maritime power.
NotesThe Sea Peoples were several groups whose identity and chronology remain uncertain. This counterfactual assumes they formed a single maritime state and kept it intact until Britain's rise as an oceanic power, roughly twenty-five centuries later. Such continuity would give trade and economic activity a long-established center. Britain would have to displace a maritime power with an exceptional accumulated commercial advantage. Supplanting it could take a very long time or prove impossible under the premise.