The benthic zone is the ecological region at the lowest level of a body of water such as an ocean or a lake, including the sediment surface and some sub-surface layers. Organisms living in this zone are called benthos. They generally live in close relationship with the substrate bottom; many such organisms are permanently attached to the bottom. The superficial layer of the soil lining the given body of water, the benthic boundary layer, is an integral part of the benthic zone, as it greatly influences the biological activity which takes place there. Examples of contact soil layers include sand bottoms, rocky outcrops, coral, and bay mud.

The benthic region of the ocean begins at the shore line (intertidal or eulittoral zone) and extends downward along the surface of the continental shelf out to sea. The continental shelf is a gently sloping benthic region that extends away from the land mass. At the continental shelf edge, usually about 200 meters deep, the gradient greatly increases and is known as the continental slope. The continental slope drops down to the deep sea floor. The deep-sea floor is called the abyssal plain and is usually about 4,000 meters deep. The ocean floor is not all flat but has submarine ridges and deep ocean trenches known as the hadal zone.

Ioánnis Fokás (Greek: Ιωάννης Φωκάς), better known by the Spanish transcription of his name, Juan de Fuca (born 1536 on the Ionian island of Cefalonia; died there 1602), was a Greek-born maritime pilot in the service of the king of Spain, Philip II. He is best known for his claim to have explored the Strait of Anián, now known as the Strait of Juan de Fuca, between Vancouver Island, now part of British Columbia, Canada, and northwestern Washington State, United States.

Fokás's grandfather, Emmanouíl Fokás (Gk: Εμμανουήλ Φωκάς), fled Constantinople at its fall in 1453, accompanied by his brother Andrónikos (Gk: Ανδρόνικος). The two settled first in the Peloponnese, where Andrónikos remained, but in 1470 Emmanouíl moved to the island of Cefalonia. Iákovos (Gk: Ιάκωβος), Ioánnis's father established himself in the village of Valerianos (Gk: Βαλεριάνος) on the island and came to be known as "the Valeriáno Fokás" (Gk: ο Φωκάς ο Βαλεριάνος) to distinguish him from his brothers.

It was in this village of Valeriáno that Fokás was born in 1536. Little to nothing is known about his life before he entered the service of Spain, some time around 1555.