The business and all bookings were in English however the tour was in French with no advisory of such. I understand it's a bilingual province, however a notice that the tour would be in French would have been nice, especially because the booking and signage were all in English. Caves were quite neat and the tour guide seemed like he was telling history about how they were formed which is cool. Very nice snack near the end - supplied by tour guide! Last thing which seemed funny was as everyone was paying (at the end), and speaking together in French, everyone got about 30% - 50% off. When I went up to pay and there was nothing lowered on my price I curiously asked if there were any discounts, such as a student one or the ones everyone else got without handing anything over and just got a "no discount" response. A slight explanation would have been nice. But I expected to pay full price at beginning of trip so not too distraught on that one.
Overall I would recommend the tour if you have the money and a few hours to kill. Just make sure your tour is in your desired language :)
Side note: Very cute cafe within same building, smells like good coffee.
Edit/Response to owner: thank you for the prompt response! Fastest ever, raising review to four stars as this customer service has made the overall experience more enjoyable :D.
Yes upon arrival I did say I could only speak English and it would be nice if it was in English or partially as it seemed other patrons were all bilingual, as they spoke to me in English at beginning and throughout. He said he'd try but two other guests ended up translating portions on the fly, which was very nice of them. Thank you for the trip redo offer, if I ever make it back out to St. Martins I'll definitely stop by for an English tour. Cheers