All three will be run by people who have worked as skippers on tourism vessel Monarch, though each offers different experiences, from fishing to Maori culture to viewing harbour shipwreck sites.
They enter a booming tourism market.
Visitor arrivals to New Zealand are expected to increase from 3.7 million last year to 5.1 million in 2024.
Last cruise ship season, Dunedin had 87 visits, and more than 100 are booked for the coming season.
She is bringing a new custom-built vessel from Nelson later this month.
Ms McGregor said she had worked as a guide at the Royal Albatross Centre and had been a skipper on the Monarch.
She planned two-hour tours in a fast, shallow-draft vessel that could land on beaches.
That meant the vessel could visit shipwreck sites near the shore, offload passengers at beaches and go offshore in a hurry if there was something to see.
Ms McGregor said the tourism boom had helped her decision to start her business.
"It’s given me confidence to go forward because tourism is increasing."
Former Department of Conservation ranger Lyndon Perriman and business partner James Karawana are planning to start Horizon Tours in September.
Mr Perriman said he would use his knowledge of local wildlife and Mr Karawana’s knowledge of Maori culture for their operation.
There would be tours that would take cruise ship passengers through the city to look at heritage buildings, before heading out to the peninsula to see flora and wildlife, and take a journey through Maori history and culture. A ride on the Monarch would be included.
There would be a visit, guided by the two men, to the Otakou marae, and visits to see wildlife at the likes of Taiaroa Head, Allans Beach and Sandfly Bay.
Mr Perriman said the cruise ship market was booming, and people wanted expert guides for their tours.
Ricky Fife’s Ezifish Charters has applied to Doc for a marine mammal permit to operate a commercial tour to view whales, dolphins and seals.
While the primary activity of his business was fishing, there was always wildlife around when he was on the water, something passengers were keen to see.
His Careys Bay-based operation would view marine mammals at areas including Taiaroa Head, Harington Point and Aramoana.
Monarch owner Neil Harraway said time would tell if there was room for other tour operators on the harbour, but there was a "cluster effect" that could help businesses, for instance, if there were a number of cafes in one area.
"The cluster effect works, and the more offerings, the more attractive the town becomes."
