Ytre Oslofjord

Ytre Oslofjord is the outer section of the Oslofjord system, extending 65 kilometers from the Hurumlandet peninsula to the Færder Lighthouse. The waterway narrows at Drøbak Sound, which marks a natural gateway between this outer fjord and the inner parts closer to Oslo.

The waterway bore the name Christianiafjorden from 1624 to 1925, reflecting Oslo's former identity. Before that, it was simply called Fold.

The fjord waters influence the daily activities of 1.6 million residents living in municipalities along its shores, representing a significant portion of Norway's population.

This inlet remains warm year-round and is Norway's warmest body of water, with an average of 7.5 degrees Celsius throughout the year. Water temperatures peak in July at around 17 degrees Celsius, making it suitable for swimming and water activities.

Drøbak Sound is a natural narrowing where waters shift between the outer fjord and the inner basin. This bottleneck has made it a crucial passage for marine traffic and navigation throughout history.