Lobby group Friends of Marineland battled unsuccessfully in the High Court to have Marineland maintained as an animal sanctuary.
Friends spokeswoman Emily Otto had an "Oh, please No!" response when first reading of the cable ski concept, and the possibility of the site being taken over by water skiers and wake-boarders.
She called on Marineland supporters to speak up.
"Now more than ever, Marineland needs your support," she said.
"While this is still only an idea at this stage, in short, it looks like it involves demolishing the current site, getting rid of all the marine animals and turning the whole area into an artificial lake for thrill-seekers on water skis or wakeboards attached to a cable overhead.
"This would not be something for all ages to enjoy and is not something which promotes marine conservation or raises awareness about our precious marine life," she said.
"If you like the Friends of Marineland's proposal for an education-focused marine animal sanctuary (including a marine animals hospital) then please, tell the Napier City Council."
Businessman and Friends supporter Rodney Green, whose hotel interests include the Quality Inn opposite Marineland, lauded the council plans which also propose a second big-money item - a wave park towards the northern end of the Parade.
Other proposed ideas include a range of mainly free activities and open areas, some already existing and others including a junior bike track, a BMX jump park, a pier and other work, all in the approved or planning stages.
"It's a wonderful step forward, well overdue," Mr Green said. "The ideas are very, very good.
"But I still feel not enough was done to keep Marineland as a sea-life park, without [performing] dolphins."
Generally, the proposals were being well received yesterday, with some relief after delays in setting a path for the future.