The dramatic version of this animal is a sequence of about one second. The true day is longer and duller, which is the compliment. A blue-ringed octopus spends it in or near the den, matching the rubble, taking small prey when the chance is good, and keeping the warning lights off. They are often described as daytime hunters, which distinguishes them from a lot of nocturnal octopuses, but a daytime hunter in a crevice is still mostly a hidden one.
Movement has two gears. They crawl, which is the ordinary gear, arms doing the walking. They can also swim the octopus way, by drawing water into the mantle and sending it out through the funnel, a short jet rather than a cruise. Neither gear is an attack on a person standing in the pool. Faced with danger, the first instinct that observers report is flight. The display is the second step, when leaving has not worked. The bite is the third, when the animal is cornered and touched.
That order is the whole ethics of a shore walk. An animal with a three-stage answer, of which only the last is dangerous, is an animal you can share a beach with. You simply decline to become stage three. Stepping carefully, not turning rocks onto your feet, and not carrying a small octopus back to a towel are the entire method.
It is also worth saying what the day is not. These are not animals that hunt people, guard a territory against swimmers, or leap from the water. The folklore needs a monster because the toxin is real. The animal, on an ordinary Tuesday, needs a crab and a hole.