Two days later, on 20 December, during an attempt to sneak into the harbor she got entangled in an anti-submarine net and could not free herself.

An anti-submarine net is a device placed across the mouth of a harbour or a strait for protection against submarines.

A net layer's primary function was to lay and maintain steel anti-torpedo or anti-submarine nets.

There had been anti-submarine nets off the end of the quays.

However, Mariotte failed to negotiate the anti-submarine net that E14 had eluded and was forced to the surface.

While there were anti-submarine nets in place over the three main entrances, they comprised only single-stranded looped wire.

During World War I the chain was replaced with anti-submarine nets.

Except for the Gan Channel, the other openings were permanently closed by anti-submarine nets.

A large army garrison protected the city with forts, gun batteries, and anti-submarine nets.

The loading of fuel was not completed until after the anti-submarine nets had been raised for the night.