Newly formed sea ice is often salty because as it freezes small pockets of salty water called 'brine' are trapped between the ice crystals.
The older the sea ice the less salty it becomes as all the 'brine' drains out of it. So, if you are on the Arctic Ocean and looking for some ice to melt down to make drinking water, you are better off looking for the oldest ice you can find......
.....but wait, how can you tell what is old and what is new ice?
The clue is in the colour of any melt pools. If the melt pools are a dark blue then this is new, first year ice. If the melt pools are lighter or turquoise in colour, then this is older ice that has been around for more than one summer season. Easy!