Secret achievements in Monkey Island: SE

Question

Does anyone know what the secret achievements in Monkey Island: SE are, and how to get them? (I love Monkey Island, and was somewhat shocked to just now look at my achievements and see that not only are there four I didn't get -- but that they're secret, so I don't know how to get them!)

Answer 1

All achievements are Secret Achievements in The Secret of Monkey Island: Special Edition, so here is the list of all Achievements and their descriptions. (source)

• The Three Trials
  Completed Part One: The Three Trials. Guybrush proved himself worthy to be a pirate.

• The Journey
  Complete Part Two: The Journey. Guybrush used a voodoo spell to travel to Monkey Island™

• Under Monkey Island
  Completed Part Three: Under Monkey Island. Guybrush traveled into the Monkey Head and got the root.

• Guybrush Kicks Butt
  Completed Last Part: Guybrush Kicks Butt. Guybrush stopped LeChuck from marrying Elaine Marley.

• Sharp Tongue
  Guybrush learned all of the insults, and is the wittiest/deadliest pirate what ever swung a sword.

• Ten Minutes Later...
  Guybrush can hold his breath for 10 minutes, but not any longer than that.

• Escape Artist
  Escaped from the monkey island cannibals hut 5 times.

• RecordKeeper
  Collected all of the notes and memos sent between Herman Toothrot, LeChuck and the Cannibals.

• Human Cannonball
  Finished the entire game in record time. We hope you were wearing a helmet!

• Old School
  Experienced the original, classic adventure game, as it was in the early 90s.

• Determined
  Completed the game without using any hints.

• Marooned Everyone
  Re-marooned Herman Toothrot and marooned Carla, Otis and Meathook on Monkey Island™.

Answer 2

I think "Marooned Everyone" requires you to play through twice, once sinking the boat with the rock shooter, and once without.