challenge: What significant discovery was made by the RV Southern Surveyor in 2006 off the coast of Rottnest Island, Western Australia?
  
  A. A new species of coral in the Great Barrier Reef
  B. A submerged city between Fiji and Samoa
  C. A 200 km diameter vortex in the waters above the Perth Canyon
  D. A new type of submarine volcano
  Answer: 