A pipeline leak is causing a massive fish kill of thousands in the waters off Honolulu, but forget the usual suspects, diesel fuel or tar sands bitumen. The culprit this time is molasses.

Divers reported that thousands of fish have suffocated in Honolulu Harbor after 1,400 tons—233,000 gallons, enough to fill seven rail cars or one-third of an Olympic-sized pool—of the sticky sweet stuff oozed from a pipeline on Monday September 9, the Associated Press reported.

“There’s nothing alive there at all,” said Roger White, a diver, to NBC News’s Hawaii affiliate, KHNL after filming dead marine life scattered at the bottom of the harbor. “Everything is dead. They’re all dead and they’re all just lying across the bottom—hundreds and hundreds, thousands.”

Environmentalists said this was just the beginning. The spill, which had been repaired by Tuesday, could have long-term repercussions.

“It’s in a bay, so there’s not a lot of circulation,” said David Field, a marine scientist, to NBC. “So you’re not going to have flushing of this water out. So in this area where it occurred, you’re going to see the effects of for probably a long time.”

Moreover, the effects could be widespread as the spill dissipates, he said. Tides and currents are propelling the dark-brown molasses plume from Honolulu Harbor into the Keehi Lagoon, the health department said. From there it will dissipate into the ocean.

"As water does leave this bay area and goes out into the neighboring ocean we can expect the effects in the long term in days, weeks months and probably years to spread out over some of the south shore reefs,” Field said. "I think there are going to be a lot more effects down the line that aren't so obvious and don't make such a big impression as the fish on the video do."

In the short term, boaters and state officials were collecting hundreds of dead fish from the harbor and warning the public about a potential influx of predators such as sharks and barracuda, attracted by the food.

“The public is advised not to enter the ocean if they notice a brown color in the water,” the state’s health department said in a statement. “While molasses is not harmful to the public directly, the substance is polluting the water, causing fish to die and could lead to an increase in predator species such as sharks, barracuda and eels. The nutrient rich liquid could also cause unusual growth in marine algae, stimulate an increase in harmful bacteria and trigger other environmental impacts.”

The shipping company whose pipe sprung a leak, Matson Navigation Co., had repaired the leak and ceased operations pending its investigation.

"We have ceased our molasses operation, sealed the pipe and closed all the valves," spokesman Jeff Hull told NBC News, as the company released a statement expressing regret at the spill and noting its 130-year, incident-free history in the area. "It's all shut down at the moment.' ”