1967's The Dolphins of Altair is the beginning of Margaret St. Clair's "psychedelic" period. It would continue on with The Shadow People (1969) and conclude with The Dancers of Noyo (1973). Although the plots of the book are significantly different, her use of the California coast, environmentalism, and counter-cultures all link these books. They are also told in the first person. Dolphins is told from the viewpoint of a dolphin historian named Amtor. At the beginning of the novel, the dolphins, or sea people as they refer to themselves, have become distressed.The seas are becoming increasing polluted. Humans are capturing and placing dolphins into naval research stations for underwater warfare training. The dolphins form a council and decide to reach out telepathically to three people: Madeline Paxton, a secretary at the Half Moon Bay naval research station; Sven Erikson, a former soldier and dock worker; and Dr. Edward Lawrence, a clinical psychiatrist who works for the US navy. Madeline proves to the most receptive to the Dolphins' cries for help. Sven later joins her. Finally, Dr. Lawrence hires a boat to drop him off on the a rock far off the California coast. Together, they concoct a plan to free the imprisoned dolphins from the research station. Using Sven as a courier, they steal a powerful under water mine from a weapons shipment and give it to the dolphins. The mine is then dropped by one of the dolphins into a deep trench off the coast where it explodes, causing an earthquake. The earthquake, timed to be a minor one and on a Sunday evening to minimize loss of human life, bursts open the dolphin pens, freeing the sea people to the open ocean. But then Dr. Lawrence disappears from the rock, with no explanation given. Moments later, the rock is strafed by a navy plane. Several of the dolphins are killed and Madeline is wounded. Why did Dr. Lawrence betray them? Do the dolphins have time to come up with a new strategy now that war between them and the "splits" (humans) seem to be immediate?

a One of the more interesting ideas put forth in the book is that humans and dolphins originated from the same species. According to the dolphin historian, millions of years ago, the commons ancestors of both creatures migrated to earth from a planet in orbit around the star Altair. Over the millennia, some of the settlers stayed on land while others returned to their natural environment, the water. At some point in the distant past, the land dwellers began mating with terrestrial primates, producing humans. 

This is the origin of "The Covenant" mentioned in Dancers of Noyo.

The book is well-plotted and easy to dissolve into.

 if you are in prisional mode

Much of it consists of conversations between the dolphins and their human allies trying to figure out the least destructive means to strike back at the surface dwellers. This could be the original ecological science fiction novel.