When is it safe to go kayaking and hiking after abdominoplasty?

Every surgeon has a different postoperative protocol.  It's best to speak to your surgeon because he/she may prescribe something different due to something specific in your case.
I usually tell patients that they can return to normal activity between 4-6 weeks.  I have them keep the binder on for at least 4 weeks. No heavy lifting for 4 weeks minimum. 
Usually at about 4 weeks, your body will tell you what you can and cannot tolerate. 

Dear Jlc0503,every plastic surgeon has his own postoperative protocol which he recommends to his patients. I would suggest you to discuss this with your plastic surgeon.Daniel Barrett, MD
Certified, American Board of Plastic Surgery
Member, American Society of Plastic Surgery
Member, American Society of Aesthetic Plastic Surgery

Congratulations on your surgery! This question is best answered by your surgeon who is most familiar with your surgery and how you've been progressing through recovery. I advise my patients that they can return to strenuous activities after six weeks. Please note that you are still healing and should increase activity gradually. You may find you tire more easily and are sore after new or extended activity.

Hello dear!!
Thanks for the question and provided information as well.
I recommend my patients to wait at least 6 weeks before resuming their workout rutine (cardio, lift, etc.), but every case is different, so I suggest you to follow up close with your plastic surgeon.
Hope this is helpful. Good luck :)

Thanks for reaching out, and congrats on your recent procedure! I would suggest you get cleared by your surgeon. Follow his/hers postop protocols, they know your case best. Best of luck! Dr. Kachenmeister

but I'm not so you should always clear the resumption of activities with your surgeon since you will be going back to him/her if any complications arise from your increased activities.  Surgeons all have different protocols so you chose your surgeon and you should follow your surgeon's routines for returning to activities following your tummy tuck.

Every surgeon has their own recommendations for returning
to physical activity that is based on the patient on the patient and procedure.
It is important that you follow your surgeon’s post-operative care
instructions. We recommend consulting your surgeon to further discuss your
questions and concerns.

First of all, congratulations on your tummy tuck, Jlc0503!
Usually, you can go back to your normal activities six weeks after your surgery, as long as you didn’t develop any complications and you’re healing well.
Still, it’s best if you would ask for advice from your reputable and board-certified plastic surgeon so that he can give you clearance before you engage in those activities. After all, it’s best to do it gradually so as not to put too much stress to your body.
Good luck!

Hi darling.. Thank you for your question!I'd recommend consulting your PS before making any exercise related activity in order to avoid further complications. Remember to always stick to what your PS says, He/She is the one in charge of your journey and knows exactly what is better for you.Kind regards,Dr. Jiménez Toribio Plastic and Reconstructive Surgeon.