Yup - Just don't dunk the housing.
I've hunted beaches a plenty with the 250, and have gone a couple feet up the shaft in water.
In practice, this is nearly useless unless you have someone to help you, as when you find something its rather difficult to retrieve an object with one hand holding the detector.
I usually have my kids to help out, but they quickly lose interest and go running off to build a sand castle or something ... So in practice I pretty much confine myself to waterline searches and the beach itself.