What is a growler from the book Ernest Shackleton?

Answer 1

A Growler is a very small iceberg which is less than 1 metre (3.3 ft) high and less then 5 metres (16 ft) long.

When trapped air escapes as the iceberg melts, it sometimes makes a sound like the growl of an animal, and that's how growlers got their name.

Answer 2

In the book "Endurance: Shackleton's Incredible Voyage" by Alfred Lansing, a growler refers to a small iceberg. These growlers could be particularly dangerous for ships as they were difficult to spot and could potentially damage or sink a vessel.