"Twilight Zone: Hidden Wonders of the Ocean" was jointly created by ARTECHOUSE ... According to WHOI, the twilight zone refers to a specific depth within the water, not a latitude or longitude.

The ocean's twilight zone is deep, dark, and—according to new research—iron deficient. No sunlight reaches this region 200 to 1,000 meters below the sea surface, where levels of iron ...

To estimate the biomass of fish in the twilight zone – the area of ocean at 200-1000m below sea level – scientists used acoustic instruments called echo-sounders.

Sunlight, the lifeblood of the ocean’s surface, penetrates only to a certain depth—around 650 feet ... Beyond this limit lies the twilight zone, where light begins to fade, and further ...