Booking Rio Bueno Tubing after arriving in Falmouth?

I understand there is a taxi area at the end of the main street in Falmouth. We are not sure what we'll be in the mood to do once we get there, but are wondering if we decide to go tubing on the Rio Buena River can we do it without making reservations or arranging it in advance? Wanting to know if we can just take taxi there? (If so, anyone have an idea of the taxi cost?) Or does anyone know if there will be tour hawkers or info. booths offering this tour to arriving cruise passengers? We don't really want to book our ship's excurson. I know there are a few tour operators we could book with independently, but we don't want to lock ourselves in ahead of time.

Thanks for any info!