Abyssal Borders.

At the edge of the continental shelf lies the most dramatic transition on Earth: the plunge into the Aphotic zone.

The Continental Slope represents the true edge of the continent. Here, the gradient increases sharply, descending thousands of meters toward the ocean floor. This slope is often scarred by submarine canyons—massive underwater gorges carved by turbidity currents, which are essentially underwater avalanches of sand and silt.

As the slope levels out into the Continental Rise, we find the "Abyssal Plain"—one of the flattest, most mysterious places on the planet. This border is more than just a depth change; it is a thermal and pressure boundary that separates the sun-driven surface world from the eternal, cold dark of the deep ocean.