A Sonos Move or a pair of Sonos 1's

Weakness:

• Sonos drops support of their products before the end of their lifespan.
• Cost: you can probably find something with the same feature set for $100 that will offer the same sound.

If you have the $400 burning a hole in your pocket and need a waterproof, wireless speaker, check out the DemerBox DB2. Ours spends weeks on our whitewater raft, and is still going strong.

I didn't mean to sound like someone who was burned by Sonos. With the exception of my river box, all my equipment is connected by copper. Ive never owned any of their products. I just didn't want the OP to make the mistake.  If you're going to get burned by tech evolution, do it with cheap, disposable products, not expensive disposable products.