SeaWorld shares just took another nasty plunge on Tuesday.

The struggling theme park operator’s stock dropped as much as 18 percent after it said 353,000 fewer people visited its parks in the first half of 2017 compared with a year ago.

It was the latest blow in a brutal summer for SeaWorld, which remains haunted by the public reaction to “Blackfish,” the 2013 documentary that exposed the park’s poor treatment of its killer whales and their trainers.

In addition to seeing SeaWorld shares fall 32 percent this year, shareholders have had to deal with a board that has ignored their wishes.

On June 14, shareholders, in a nonbinding vote, failed to support Chairman David D’Alessandro. Nonetheless, the board decided to keep D’Alessandro in place for the rest of 2017.

The board decided to refuse D’Alessandro’s resignation because of “a number of factors,” including his seven-year board tenure and experience, it said in a regulatory filing.

Since the anti-D’Alessandro vote, SeaWorld shares have dipped 25.2 percent, to Tuesday’s close at $12.76 — down 6.3 percent for the day.

Reps from SeaWorld declined to comment on Tuesday.

Last week, Chief Financial Officer Peter Crage quit after holding the job for only two years.

Second-quarter losses reported on Tuesday amounted to $2.05 a share due largely to a $269.3 million write-off of its Orlando park. During last year’s second quarter, SeaWorld reported a 21 cent profit.

“To be clear, we are not satisfied with our results,” Chief Executive Joel Manby said on a call with analysts Tuesday.