What is described in Guo Moruo's poem "Wang Yang is a piece of indigo, and small fish and coral are painted on a screen"?

In the Yellow Sea south of zhuanghe city, Liaoning Province, there are a group of beautiful islands named Neptune Nine Islands. Neptune's Nine Islands * * consists of nine small islands. Here, every island is like a painting. Every island is a poem. Each island is very small, the largest is less than 5 square kilometers, and the smallest is about the size of a football field. There are many rocks near the island, which are strange and beautiful. The old gentleman Guo Moruo once wrote a poem here: "The boat hangs in front of the nest and the sun shines high." Wang Yang is green in indigo, and small fish corals are painted on the screen. "