More numbers will descend on the wharf in the coming days.
If the three tour companies - Fullers, Explore NZ and Mack Attack - do not enter into new negotiations with the trust, chairman Rau Hoskins said they would consider a blockade of the hole's entrance.
"It will be about us making it very clear to both the operator and the tourist that there is a significant issue here and we feel that our mana is being trampled on by these operators," Mr Hoskins said.
The row first erupted in 1987 when Fullers raised a flag on the Maori freehold island Motu Kokako, also known as Piercy Island.
The next year, the tour operator agreed to pay a portion of each fare to the trust. When another tour operator started a similar cruise, the trust and Fullers took the firm to court, alleging trespass.
The High Court threw out the case in 1992, ruling that access to the open sea could not be impeded under maritime law. Fullers then stopped paying.
Mack Attack and Explore NZ did not respond to APNZ queries.
Fullers Greatsights general manager Charles Parker refused to comment on the threat of a blockade, but did say: "Fullers GreatSights has, in good faith, entered into numerous discussions with the trust over the past five years.
"This culminated in an offer to work with the trust to ensure their mana on the island is properly recognised by Fullers GreatSights. Fullers GreatSights has never received a response to that offer."