@Background Pony #907F  
Well, the unicorn Waterfire is confirmed as having a diving talent, but of course, personality and color scheme change the Cutie Mark: Waterfire is a redhead, so her CM has a flame above squiggles representing water, she has an azure coat and blue eyes, so lighter blue waves are used to represent water.
 
And while the diving mark from the Cutie Pox may look like 3 bubbles, two ponies can have similiar Cutie Marks for completely different talents, and Derpy has seven bubbles. (which could very well be a bubble column.)
 
And Minuette and Time Turner have completely different talents- Doc’s is a smart tinkerer and clockmaker assisting all the clocks and other similiar contraptions, and propably has his own time-machine. Colgate is a dentist with a lot of other hobbies, who has magic that permits her to find time for all of them, basically her talent is time-based magic and time manipulation (possibly even time-travel? Is she a living TARDIS-toothpaste hybrid?).
 
But they both have an hourglass on their flank.

Well, judging from the pony pox book, diving is her special talent.

:D I’m so glad this guy’s stuff is getting picked up on.