Hawaiian giant octopus
The giant Pacific octopus is the largest known octopus species, with the longest confirmed specimen reaching 31 feet. However, the largest octopus species known to inhabit Hawaii is the seven-arm octopus, with the longest known specimen being 9 feet. Although gigantic octopuses are usually associated with the Atlantic, there have occasionally been reports of an elusive, much larger octopus species roaming the banks and reefs of the archipelago. These Hawaiian giant octopuses are greyish-brown in colour, being 30 to 70 feet long and are primarily seen in shallow waters, especially around turtle nesting grounds.
On the December 15th, 1932 issue of The Syracuse Herald, there was an article about a giant octopus seen off Maui. According to the article, Henry Sylva, the son of a county official, as well as multiple fishermen reported seeing an octopus with 20-foot arms dragging itself across the rocky intertidal area of the shore.
In 1928, a Navy SEAL named Robert Aiken was stationed in Pearl Harbour, on Oahu. Remarkably, during his career, he encountered this cryptid over six times. This of course garnered a lot of attention and ridicule, and in 1935, he went to one of the locations with a camera crew, and they actually photographed a dead specimen splayed out on the rocks (below). It's unknown if they found it dead, or they killed it and placed it there for the photo so Aiken could pose next to it to showcase its size, which appears to be about 40 feet.
In 1950, a man named Madison Rigdon claimed to have seen an octopus the size of a car being brutally killed and ripped apart by sharks off Lahilahi point. He described the octopus as being 30 feet, greyish brown and having suckers the size of dinner plates. He watched as it was frantically smacking the sharks with its enormous tentacles while spraying a cloud of ink throughout the water. That same year, an Indigenous Hawaiian man named Van Ako saw a 75-foot long octopus hunting turtles at a reef. It is unclear if there are any more recent sightings. There have been some reports of giant octopuses in the Pacific outside the Hawaiian archipelago, most recently a badly decomposed carcass of what appeared to be a 32-foot specimen of a seven-arm octopus was found in the Chatham Islands east of North and South Island in New Zealand.