The words “private island” conjure up visions of mai tais, palm trees and solitary afternoons on a white sand beach.

Red Rock Island is not that kind of island.

It is a six-acre, dome-shaped outcropping that is tricky to reach and even trickier to explore. Its sparse plant life consists of scraggly shrubs and pines, along with thickets of poison oak. Its beaches are rocky, its cliffs steep.

Forget mai tais. This island doesn’t have a bar, let alone trails, potable water, electricity or structures of any sort. You can take a private boat there, but it has no dock. You can fly a helicopter there, but it has no landing pad.

And for $25 million, it can all be yours.

“We believe this is like owning a Leonardo da Vinci or a Rothko,” said Chris Lim, a San Francisco real estate broker who represents the seller. “This is something someone would want in their portfolio like art or a sculpture.”