Michael Dukakis launched his strongest attack yet on George Bush's environmental record Saturday, accusing his Republican rival of "trying to fool Mother Nature" with his stand on off-shore drilling.

Dukakis, bundled against a chilly blanket of fog in a bright red sweater, told a supportive crowd gathered on the shore of San Francisco Bay of his plans to designate large sections of coastline as a marine sanctuary.With the fog-shrouded Golden Gate Bridge behind him, the Democratic nominee said if elected president he would create a new National Oceans Protection policy to guarantee protection of environmentally sensitive parts of the coast.

"In a Dukakis administration," the Massachusetts governor said, "we won't need an act of Congress to protect fragile areas like the Cordell Bank (north of San Francisco) and Monterey Bay. We'll do it with the stroke of a pen in the Oval Office."

Dukakis, who previously has accused the vice president of flip-flopping on the environmental issue, proposed making sanctuaries of Santa Monica Bay and the California coast from Big Sur north to Oregon.

"George Bush can't fool Mother Nature, and he can't fool the people of California, either," Dukakis said of Bush's stand on off-shore drilling.

"I'll send this (the Reagan) administration's five-year oil drilling plan back where it belongs - to the drawing board," he said.

California's Democratic congressional delegation has been able to stave off the proposed drilling off the state's coastline for eight years but only through complex appropriations maneuvers.

Bush took time off Saturday from his campaign and planned to travel Sunday to California. Environmental issues could be the deciding factor in winning California, with 47 votes, the fattest plum in the electoral sweepstakes. Recent state polls show Bush and Dukakis running neck and neck.

A poll released Saturday by The Chicago Sun-Times also showed Bush and Dukakis in a dead heat in Illinois, with each candidate favored by 44 percent of the state's registered voters. Illinois is another crucial state in the Nov. 8 election. No Republican presidential candidate has ever won without Illinois.

Dukakis also picked up two endorsements Saturday. The normally conservative Seattle Times, the largest newspaper in Washington, for the first time since 1930 endorsed a Democrat.

"The Massachusetts governor has a broader, deeper understanding of the economies of the states and the nation," the Times said Sunday.

Dukakis was endorsed by the Maryland Campaign for the Environment '88, which said Bush was a "co-pilot" in a Reagan administration assault on the environment.

The vice presidential candidates, Sens. Lloyd Bentsen and Dan Quayle, spent much of Saturday preparing for their face-to-face debate Wednesday night in Omaha, Neb.

A Quayle spokesman said the Indiana senator met with President Reagan at the White House and later had a mock debate with Sen. Bob Packwood, R-Ore., standing in for Bentsen.

Bentsen spoke briefly to reporters in Washington after a strategy session with four fellow Democrats in Congress. He said simply, "Their advice is to be myself" in the debate.