Tsunamis
Tsunamis are one of the most dangerous hazards in the ocean. A tsunami is formed when two plates collide and make enormous pressure, the pressure is then brought to the surface of the ocean where it makes four-way waves. These waves are the tsunamis. They grow in strength the closer they get to shore.
Rip Currents
Rip currents are another dangerous ocean hazard. Rip currents are made when breakers cross sand bars off the shore. The water then travels back to sea through gaps in the sand bar creating a rip current. Once caught in a rip current you shouldn't swim against the current you should swim to the side to escape it.
Jellyfish
Jellyfish are a ocean hazard that might not be well known. People can get stung by a jellyfish due to shared habitats when you are swimming in the Great Barrier Reef. The most common jellyfish you would get stung by are the Box Jellyfish and the Irukandji Jellyfish. Both of these jellyfish like warm waters, so during the summertime more of these jellyfish appear.