Good bluetooth speakers to pair up for stereo?

A little off our usual musings, but some advice would be appreciated.

My daughter wants a decent bluetooth speaker to play music from her iThing. Fine, I said, I’ll go through some reviews and choose a good one for you. Yes, dear, I’ll make sure it’s a nice colour too.

Then I (dangerously) started musing. I’d quite like one too for holidays and the like. Wait a minute, I could buy the same model as I get her and we might be able to pair them up in stereo. Can it be done?

A quick Google suggested that this was possible but only with certain models. The reviews I found were from the tech/computer sector and so their assessment of SQ was basic at best by our standards.

So: recommendations please for

1) very portable bluetooth speakers which have

2) battery power at least as an option (onboard rechargeable probably best)

3) waterproof, ideally

4) for under £100 per piece and which

5) can be paired up to act in stereo

6) and which sound great. Obviously.

Thanks,

Mark