Dutch - 3/30/2014 3:07 PM
First, did your use of Scuba Earth predate the filing date for their trademark?
Second, Is your trademark for Dive Buddy or DiveBuddy? Scour their website and books for any use of your trademark and not how often and in what type of media that appears.
Third, Do the research as mentioned by JonathanMarc82.
Fourth, sit back and relax until they actually send you a real Cease and Desist registered letter.
Lastly, Crowdsource the counting of violations of your trademark. that is what we are here for.