Underwater navigation

Out on the water a chart plotter provides a similar level of functionality for boaties, enabling them to find their favourite Spot X or locate new positions of interest based on structure visible on the chart.

So, it may be a surprise to most people that there is still no simple solution to navigating once you drop beneath the surface. Radio waves simply do not penetrate through water, except for extremely low frequencies. Hence GPS signals cannot be received, and two-way underwater radios are not possible.

To make it worse, visibility underwater in most of New Zealand’s coastal waters is limited so it is very easy for divers to lose their sense of direction. Sometimes even being just five metres away from your reference point (such as the boat’s anchor line) means you cannot see it, so it is easy to get lost. Equally, the skipper