Olympus have released a TG-6.  Looks a bit like a TG-5 with 'one' added.  Better screen and a few other tweaks. I was still umming and arrghing over a TG-5.  If the TG-5 gets rather discounted, well why not? Keeping to 12 mega pixels seems sane for low light stuff.
https://www.olympus.co.uk/site/en/c/cameras/tough/tough_cameras/tg_6/index.html

Wow, there is practically no difference at all (comparison link)! It even looks pretty much identical.

The screen resolution is a considerable step up, but I'd not identified the resolution with the current model as a problem, so I would still go for the TG-5 if it's any cheaper whatsoever.

You may also find a secondhand TG-5 for sale at a good price where someone is upgrading to the TG-6 because they want the latest model. 
 
 
 
Maj. 

The tg6 claims to have an anti fog lens and extra focus stacking options if you're into close ups.

Incidently I'm thinking of selling my tg4 if anyone is interested in an older (and therfore cheaper) model that still takes great underground photos

JoW said:

The tg6 claims to have an anti fog lens and extra focus stacking options if you're into close ups.

Incidently I'm thinking of selling my tg4 if anyone is interested in an older (and therfore cheaper) model that still takes great underground photos

Click to expand...

I'd be open to look at a TG-4 for work if you had any details (price etc..).