As fiction, the plot is the stuff of a paperback thriller: an environmentalist hit squad, internationally financed, schemes to blow up their arch-enemies - the boats that hunt and kill the great Pacific Ocean whales.

As fact, unfolding here now before federal grand jury, the plot is even more bizarre.

It includes , so far, several whale-lov- [WORD ILLEGIBLE] Vietnam veterans with their pocks full of $100 bills, a yellow attack [WORD ILLEGIBLE] , a huge cache of powerful [WORD ILLEGIBLE] and some of the most so- [WORD ILLEGIBLE] diving equipment avail- [WORD ILLEGIBLE] the world. Federal law enfor- [WORD ILLEGIBLE] the little group plotted to attack Soviet and Japanese whaleboats [WORD ILLEGIBLE] on the coast of Chile.

That such a plan could exist here is not unusual. Tall tales and Bizarre schemes along Florida's South Coast are about as uncommon as rhine-stones. But federal officials are convinced this one was real.

The investigators, and others with direct knowledge of the details, say the money came from an international environmental organization involved in the bitter fight over commercial whaling. But these sources could not name the group.

In July, acting on an FBI informant's tip, federal agents raided the home of a former Navy diver and demolitions expert, James R. Rose Jr., 31. Rose led them to two separate stores of buried C4 plastic explosive - enough, one agent said, to blow up a skyscraper.

Rose was charged with interstate transportation of explosives without a license. His is the only arrest in the case so far. A federal grand jury here opened an investigation late last month.

In a briefcase in Rose's small, white frame house on the outskirts of Miami, federal investigators also found 30 photographs of Soviet and Japanese whaleboats lying at anchor in the harbor at Talcahuano, Chile. In the garage they found a two-man yellow submarine.

The explosives, the sub and the photos were not an unexpected discovery, a federal law enforcement source said last week. In May the FBI informant told authorities he and Rose had purchased the C4 along with a quantity of blasting caps and 1,500 feet of detonator cord.

The tipster was identified to The Washington Post last week as Bert Caratelli, a Detroit man who has boasted of working in the past with the Central Intelligence Agency and the Detroit police. Caratelli told the FBI that, while buying the explosives, his old friend Rose told him they would be used to blow up the whaleboats docked in Chile.

The discovery of the explosives was unusual enough to make the local news here. It was even more widely reported when Rose was asked his occupation by reporters after he posted a $50,000 bond. "You might call me an environmentalist," he told them.

What the part-time carpenter and professional diver did not tell was the source of the $50,000 bond. He says now that he does not know where the money came from. "There was a lot of publicity about my motive in this," he said in an interview last week. "I guess I have friends I don't even know about."

The fact that Rose, who listed no personal assets on his bail application, could post a $50,000 bond and spend another $50,000 on an elaborate array of diving equipment - some of it more sophisticated than anything owned by U.S. intelligence agencies - has not been lost on federal investigators here.

Rose has turned down tentative offers by federal prosecutors for clemency in return for information about his financial backers. "That is the information we'd very much like to know at this point," a federal investigator said.

Rose also told the FBI informant that the project money was coming from a secret bank account set up for him in the Bahamas, federal sources said. Several hundred long-distance telephone calls - including a number to the Bahamas - originated in Rose's home here in the several months before his arrest.

A puzzling aspect of this case is its apparent similarity to a novel published in 1976 entitled "Leviathan," a fictional account of a scheme by a well-funded environmentalist group to attack and blow up Soviet and Japanese whaling ships with the help of a small submarine.

"This is a very weird case," a federal investigator said.

The discovery and publicizing of the plot have disturbed environmental groups involved in protesting commercial whaling. The Greenpeace Foundation on the West Coast, which has been the most active and vociferous in opposing Pacific whalers, last week denied any involvement with Rose or the alleged plot to attack the whaling boats.

"We had nothing to do with this," a Greenpeace spokesman said at headquarters in Vancouver, B.C. "We checked other environmental groups around the world and none of them had anything to do with it either."

Federal sources said last week that investigators have not yet been able to link Rose with any known environmental group.

Although the official court records on the case are sketchy, an examination of the records and interviews with persons close to the investigation or directly involved in the alleged plot produced this information about events leading up to the arrest of Rose:

In early March, according to records on file in U.S. District Court in Miami, Rose contacted Caratelli, whom he met five years before at a diving school in Seattle. According to FBI informant, Rose asked for help in buying explosives. Sources said Caratelli arranged for the purchase and the two men traveled to Toledo, Ohio, on March 5. Rose paid $3,9000 for the explosives, which sources said originally were purchased in Virginia.

An FBI affidavit filed in court states that Rose told Caratelli, after the purchase of plans to use the explosives "in an underwater demolition operation against whaling vessels in a foreign country."

Rose brought the explosives back to Miami and on June 6, according to the affidavit, he and Caratelli went to Biomarine Industries in Malvern, Pa., where they purchased two sets of sophisticated underwater breathing gear. The equipment, according to an official of the firm, allows a diver to remain underwater for up to 10 hours at a depth of 1,000 feet. The pair paid for the gear with $100 bills.

"They walked in with old clothes on and Rose pulled this roll of $100 bills out of his pants pocket and dropped it on the desk," said the Biomarine official. "Everything in the place stopped cold." The cost of the diving apparatus, he said, came to $36,440.

Caratelli and Rose split up after that, and the FBI addidavit said Rose was then joined by Bernard A. Reed and his brother Robert Reed. Neither man has been arrested by the FBI and both have dropped from sight since Rose's arrest.

Rose and the Reeds traveled to Gretna La., and took lessons in the use of the driving equipment from a firm lalled The Inner Space Co., according to court records.

About mid-June Rose and Bernard Reed approached the captain of The Dark Star, a 70-foot ketch moored at a marina in Fort Lauderdale. The captain, Mark Sterns, said Rose told him he planned to do some commercial diving off the Chilean coast for two weeks. Sterns agreed to charter the boat to the pair and said he thought they were treasure-hunters.

On June 29, Rose ordered the two-man sub from Underwater Propulsions Inc. in Tulsa. Two weeks later, Reed picked up the sub. paying half the $5,000 cost with $100 bills and the rest with a cashier's check.

In an interview last week, Rose declined to discuss the reason for the purchases or the source of the $100 bills.

But he said he supports the movement to stop the Pacific whaling, and he discussed the Japanese and Soviet fleets anchored in awhile. "It takes two years to repair one of those ships if someone knew how to disable them, and whales can have calves in less time than that," Rose said.

Rose denied being "a mad bomber or anything like that." But he said, "If the whaling fleet was disabled and no one was hurt, it would be a chance to save thousands of whales. That would be a cause to believe in."