Technically no electronic is absolutely waterproof, with ample time and depth any speaker will are unsuccessful, but some Bluetooth speakers are built more durable than others. Durability will likely be indicated by an official Ingress Protection (IP) rating. Let’s say you don’t care to have the most compact speaker https://www.bluetoothspeaker.top/new-bluetooth-speaker-wireless-audio-card-outdoor-waterproof-high-power-subwoofer/