The undersea North Canyon which influences the Nazaré surf, runs nearly 5000 meters (16,000 feet) deep, and approximately 230 kilometers (140 miles) long. The canyon abruptly meets the continental shelf and directs the power of the waves into massive swells under the right conditions.
Big wave season occurs from Autumn through early Spring at Praia do Norte, or "North Beach". The coastline is divided by the Promontório da Nazaré, a headland jutting westward into the Atlantic marking the boundary between North Beach, and the more sheltered Praia da Nazaré, the main beach. The tremendous waves are generated from the local currents and winds, influenced by the headland, and the largest undersea canyon in Europe called the North Canyon which channels massive volumes of water inshore.
It's extremely difficult and dangerous to paddle surf massive swells due to their speed and power. Arm strength alone isn't enough to catch these giants. During the 1990's Laird Hamilton, Buzzy Kerbox and Darrick Doerner, started using a motor-powered Zodiac to tow each other into the big waves off the north coast of Maui, Hawaii. The wave is called Pe'ahi, which is nicknamed 'Jaws'.
Originally envisioned as an IMAX film, the footage proved substantial enough to support a documentary series.
Garret McNamara and Keali'i Mamala once tow-surfed waves in Alaska generated from the calving Child's Glacier in Copper River near Cordova, Alaska.