We need a geologist on here.
In regard to people claiming to fly around visible ash clouds I was recently told by a geologist, when queried about last years debacle, that eruptions under glaciers produce a very different kind of ash. It's very similar this year, and it's like nothing like an eruption in Indonesia or for that matter in Alaska as most of it's seismic activity is far from where the massive glaciers are.
If you actually do fly a DA50 and it's not your own, have you informed the owner of the possible risk involved, including swimming ashore?