Somedays.. diving just sucks, here’s how to pick the good ones!

Reading the ocean and picking the good days isn’t as hard as you may think. And being able to read the ocean conditions on any given day will give you valuable insight allowing you to predict where the best site to dive is on any given day.

The factors that influence our experience in the ocean include, water Visibility, swell size and direction , wind speed and direction, and tides. Being able to interpret this information will greatly improve your time in the ocean.

Starting simply water visibility is simply a measurement of how far we can see through the water. This can extend up to 30-40meters on a good day in some locations, and on a bad day it can be so poor that you’re unable to see your hand with your arm outstretched. Visibility is altered by particles in the water, salinity gradients and other matter that has dissolved into the water. Typically the better the visibility, the better our dive is.

To predict visibility we need to assess to the swell and wind direction and size, the tides, and the location we wish to dive. Usually, the smaller the swell and the lighter the wind, the better the visibility as there’s a less chance of the ocean being stirred up by wild weather. Also the longer a particular spot has had with calm winds and swells the better again the visibility should be as any particles and sand in the water has had time to settle.

As an example at Boat Harbour in Sydney, and looking google maps we can see that it faces south, and has a headland to the east and west. This means that we should be entirely protected from swell and wind coming from the north and west, and mostly protected from swell and winds coming from the east. We are however open to a southerly swell. Meaning that Boat harbour would not be good to dive with a strong south swell or wind, and is best dove on a Northerly.

Conversely, Shelly Beach in Manly is exposed to the North and east, meaning that diving Shelly in north-eastly swell and wind would likely result in rough ocean conditions and poor visibility. The best swell and wind direction to dive Shelly beach based on it’s location is in a southerly.

Similarly, the size of the swell also plays an important role in affecting the ocean conditions and visibility. Generally speaking, swell size above 4ft is likely powerful enough to wash in particles and stir up the ocean bed resulting in bad visibility in most sites, even effecting sites that are optimally placed for the swell direction. Conversely, a swell size around 1-2ft shouldn’t affect a poorly placed site too badly, yet you should expect very good ocean conditions and visibility with a 1-2ft in an optimally placed dive site.

Finally, I usually like to dive most sites on the slack high tide, simply because there’s more water around, which dilutes whatever particles are already in the water.

To get access to this ocean weather information, a simple google search should be your starting point. There’s plenty of resources around which will give you swell, wind, and tide information, and then simply look at google maps and compile the information as we previously discussed to predict the dive conditions. In Australia, seabreeze, willy weather, coastalwatch and swell net are excellent resources for this.

It only takes you a few minutes before each dive, but it’l greatly improve your experience underwater – get out there, and hunt down some good visibility!