What is the most venomous jellyfish in the ocean?

The box jellyfish, also known as sea wasp, is considered to be the most venomous jellyfish in the ocean. Its venom contains toxins that attack the heart, nervous system, and skin cells, and can cause serious injury or death in humans. These jellyfish are commonly found in the waters around Australia, the Philippines, Thailand, and Malaysia.

Box jellyfish have a cube-shaped bell with up to 15 tentacles that can reach up to 10 feet in length. Their venom is delivered through the tentacles, which are covered in tiny, harpoon-like stingers that can penetrate human skin, even through wetsuits. If stung, victims may experience severe pain, difficulty breathing, heart failure, and in extreme cases, death.