Viz - Short for visibility, the horizontal range of visibility when underwater. It’s normally between 5m and 15m in Irish waters, sometimes more, sometimes less. The west coast offers the greater chance of gin clear water; this is generally following a period of easterly winds which make the sea flat. With the wind coming from the southwest the viz is still very good. What makes for poor visibility is sandy bottoms or a period of stormy weather which stirs up the bottom. The best dive sites are around rocky cliffs or big drop offs where the marine life is best.