The Yearly charts show the average Viz and Temp for the year . 
Each year has monthly charts that show the Viz, Wind direction, condition of the Sea and what the Weather was like.

The "VIZ" is considered to be the distance that you are able to see underwater. (Although it is not measured with a ruler!). Obviously this Viz is a subjective figure but they give a good indication of the excellent Viz to be obtained in Sodwana.