Alarm/immobiliser

Hi all

I'm off surfing tomorrow but this time on my own- no one to look after my keys when in water!
Question is- I have a central locking remote, which I think is the immobiliser/sets alarm as well as a key. As I need this with me to start the car what's the best way to get round not taking the immobiliser in the water? Anyone had this problem? Could I leave the remote in the car and lock doors mAnually, and just tuck key in my wetsuit?
Even if this does work- would it invalidate my insurance?
I'm off tomorrow at 5am so if anyone's about tonight to help that would be much appreciated.
Thanks

Zip lock bag?

What i do when i am diving is to have a key lock. basically a giant padlock that has a lock box as part of it. i can only fit the Fob in, not he key as well but it means i can open the back of the defender up and leave the key there

something like these

Outdoor mini key safes UK | The Safe Shop

Yes that's the last resort, though it's not ideal, pretty uncomfortable on u when surfing.
Thanks though

tie your key up in a plastic bag and bury it next to one of your wheels

Thanks, have thought about the key lock box, again wasn't sure if this invalidates the insurance?
Do you attach the lock to your bumper or something?
Sorry lost what you were saying a bit?

I see few people tucking key away...I always feel a bit un easy with that though

insert key into a balloon tie the end up and put it in your wetsuit

the one i have i simply clamp around the drivers door handle or the rear light protectors as it has a huge padlock style hasp that locks when the box locks.

the place i got mine from that does spearfishing stuff doesn't have it on the website or id link directly to it

Thanks for all the suggestions guys.
So is the leaving the remote lock/ immobiliser /alarm thing in the car a bad idea then? As I will have the actual ignition key which I can lock doors with and obviously start car.