A steady crowd of up to 20 people stopped to watch and take photos of the leopard seal.
"Everybody was very respectful, giving him the appropriate space of 20 metres."
Dr Visser said leopard seals are typically found in Antarctica and sub Antarctic islands but are also regularly found around New Zealand.
She said given the leopard seal deposited a fresh scat on the pontoon - it was evident he was feeding in the area. The scat would be analysed to see what the seal had eaten.
Leopard Seal research assistant Giverny Forbes travelled from Auckland to see the leopard seal, but he flopped into the water just minutes before she got to Whangarei.
She said this male makes it possibly three leopard seals in Northland. Owha, the well-known female leopard seal was last spotted on Saturday at One Tree Point. There is another female called Novy, but there has been no confirmed sightings recently.
Sightings and photos can be reported to 0800 leopard, leopardsealsnz@gmail.com or Leopard Seal Sightings NZ on Facebook.