Iceberg spike

Scattered in the ocean outside the Northern Water Tribe, these iceberg spikes resemble large, jagged icebergs. Waterbenders make them as a first line of defense against Fire Nation ships. They can rip through metal and sink even the largest ships. The currents in the iceberg fields are known to be extremely dangerous. The iceberg spikes are also used as cover for Water Tribe warriors who hide behind them and are able to ambush any unwanted visitors.