Poseidon's realm refers to the vast and mysterious world of the oceans. Synonyms for it can include the deep, the blue, the briny, the vast, and the watery expanse. These synonyms capture the immensity and depth of the oceans, which cover around 71% of the Earth's surface. The oceans are home to diverse marine life, from small plankton to gigantic whales and sharks. Poseidon, the Greek god of the sea, was believed to be the ruler of this vast domain and was often depicted holding a trident. Whether we call it Poseidon's realm or use one of its synonyms, we are reminded of the magnificence and power of the ocean.