Oahu is a dangerous place. I am constantly aware of and exposed to the tragedies and death surrounding the Big Blue, whether it is getting lost at sea, surfing, diving, cliff jumping, etc.
I have been diving on Oahu for the past nine years and over this time have experienced life threatening sea conditions and survival situations a few times. Somehow, I have been lucky enough to find my way out.
But does it always have to be like this?
Why do we wait to question the conditions until we are out in the middle of the sea just to find out that the currents are ripping while we are on a high speed express to Molokai?
This doesn’t have to happen! Over the last 4 years, I have been keeping a dive log. This isn’t a pointless log to track the amount of dives I have made; it is all about ocean conditions.
My log consists of wind conditions and strength, tide change, moon phase, tidal coefficient, solunar activity, fish seen, and of course, the dive location. The information gathered over the years has helped me efficiently plan my dives during optimal freedive or spearfish conditions.
For instance, Sea Tiger, a wreck that is three quarters of a mile off the Honolulu coast, is one of my favorite freediving locales. However, I don’t want to be fighting the current and diving on bowed lines when I go. I want nice, straight lines and no current. After a few logged dives on the Sea Tiger, I started to see and understand ocean patterns. Depending on the time of year, wind direction and tidal coefficient (strength of the tides) can cause the tide to switch. Logging your conditions can make the difference between experiencing the dive of your life or a survival situation.
How do tide changes affect the diving conditions?
Tidal swings are caused by the relationship between the sun and the moon. The moon, although much smaller than the sun, is closer to the earth and has a larger effect on tidal changes. Even though the sun has such a large mass, it has a relatively small effect on tidal changes due to the great distance between the earth and the sun. When the sun and the moon align together and create a full or new moon, it produces spring tides, which cause a stronger tidal coefficient, meaning a larger jump between high and low tide, thus creating stronger currents. During waxing and waning moons, the effects diminish, producing a lower tidal coefficient. Smaller jump equals weaker currents.
In addition to the moon phases, wind conditions and harbor inlets also affect tidal condition. During low tide, the Sea Tiger pulls a substantial amount of extra water from Ala Wai Harbor triggering an increase in current strength and murky water conditions. Adding a south west wind to the equation the wreck can produce exceptionally strong currents initiating another dangerous situation. In this situation the optimal time to dive is during high tide. However, just the opposite can happen during an extreme high tide and strong east winds. This tide and wind can cause the current to become too strong towards Ewa Beach, making low tide a more ideal time to dive. Reading and looking at a wind and ocean forecast before diving is an absolute must.
How to plan or decide whether to spearfish or freedive?
A full or new moon signals the time to grab your gun and go spearfish. Due to the Solunar activity, the fish tend to be quite a bit more active during this time along with the tides and currents. So how do we stay safe? This is where the dive log comes in handy. Looking back at previous dives, diving at X spot, I have experienced weaker currents diving at high tide with X wind conditions. Typically, less current will provides stronger opportunities to shoot pelagic fish.
During waxing and waning moons, I usually like to put down the gun and freedive. The fish aren’t as active and the currents are weaker producing better freediving conditions and an idyllic opportunity to work on technique and form without worrying about spearing fish.
Research is key when it comes to diving and spearing fish on Oahu. Starting a dive log will ensure that you are getting the most out of every dive you make. So next time the wind is down and the moon phase is waning or waxing, come dive with me on the lines and improve your freediving abilities!
Written by: Daniel Koval