Surfing with the Turtles (Bindi Wildlife Adventures #8) by Jess Black & Bindi Irwin

Bindi and her American friend Kelly are on a surfing tour in Mexico and the United States. Totally gnarly! Getting to surf with green sea turtles is a complete thrill. But one of their fellow surfers is acting suspiciously, and Bindi realises he's got more than beautiful waves on his mind. Be careful of the wipe-out, dude!