Port Services Manager Bruce Lochhead said the port began sponsoring the event because it was passionate about promoting healthy, active lifestyles "both amongst our team and amongst our community".
Lochhead, a keen swimmer, said the event was great for encouraging people to get in the open water and build their swim skills in a safe environment.
"We're big believers in giving back to our community. We know that our success as a business is closely linked to the health of our economy and our communities, and we're committed to doing our part to support that.
"We're particularly keen on supporting events in our back yard, and organisations that promote water skills and safety – so sponsorship of the Ocean Swim is a perfect fit for us."
He has entered every year since Napier Port became the naming sponsor and will be one of a "strong contingent" of Port staff taking to the water today, competing in the 1km race.
From 9am, around 300 swimmers are expected to compete in events including the 200m Kids dash, and individual and team races of 300m, 1km and 2.5km.
Returning due to popular demand will also be stand up paddle boarding races - of 2km and 3.5km.
Mr Adsett said although the event has grown over the years the jubilant mood afterwards and during prizegiving has remained the same.
"There's a sense of achievement. There's this feeling of, 'I've made it, I've done it'."
Today's weather was looking "ace" with Metservice forecasting fine weather and light winds.
The Napier Port Ocean Swim 2018 is organised by the Napier Aquahawks Swim Club, in association with Surf Life Saving New Zealand, Sport Hawke's Bay and TriHB
- Entries are open up until 30 minutes before each race starts. Go to napieroceanswim.co.nz for more information. First race starts at 9am, with last race is finished at midday. Prizegiving will be about 12.30pm.