Until a few months ago, I thought the Earth had four oceans: Atlantic, Pacific, Arctic and Indian. Then I found out about the Southern Ocean—the sea that surrounds the continent of Antarctica. You could claim that the waters in the area belong to the Atlantic, Pacific, and Indian oceans. But there is a boundary that separates the Southern ocean from its northern siblings—the Antarctic convergence. On my recent trip to Antarctica, I not only saw the Southern ocean but I stepped into it each time I took a Zodiac to the shore.
The Antarctic convergence is the place where cold water from Antarctica meets the warmer northern waters. Unlike a land boundary, the convergence zone fluctuates somewhat throughout the year. The icy cold water moves towards the bottom of the sea, sliding under the warmer water. It's at this point where the climate changes and along with it the marine and bird life. Although I couldn't see the exact point at which the Southern ocean began, it was obvious I was in a new ocean after our ship (M/V Polar Star) had entered it. The outside temperature was noticeably colder. Albatrosses and petrels followed the ship. Icebergs began to show on the horizon. We spotted fin whales.
When you look at the map of the Southern ocean, you'll notice that the band of water circles the globe. Because the ocean is unconstrained by land, the waves can get quite wild. The open ocean and temperature differences create intense cyclones that travel eastward around the continent. Fortunately I didn't encounter any cyclones during my trip.