Revelation 13:1. The Beast comes out of the sea. The sea is believed to represent the stormy world of politics. That is why the sea ceases to exist when everything is over (Rev. 21:1)
Problem I see with Revelations is that it’s so metaphorical - it uses language of that time and you can interpret things in so many ways - I look at the book in total ... there’s many books out there that help to understand what John was writing but again, it’s all someone’s conclusions ... wait and watch ...
Usually in the Bible symbolism seas represent people.