The following is from Regent:
People should watch the news for the latest info
Regent says:
The conditions have not improved and more airports are shutting down as a result of the ash.  We are working through the process since yesterday to try and accommodate guests who are flying.  It is impacting both the embarking and disembarking guests.  Many airlines are working with passengers but others are basically telling them they are on their own.
We are working with all the guests who we have provided air for to get them re-booked.  All cruise only guests should be directed to their airline/travel agent for assistance as there is nothing we can do operationally for them since we did not issue the air ticket. 

Jancruz1

SEVEN SEAS MARINER UPDATE

Due to the massive air traffic interruptions in and around Europe, we wish to provide an update on the situation. To allow guests that are still enroute ample time to meet the ship, Seven Seas Mariner stayed in Venice for two extra days and sailed Monday afternoon. To accommodate this change, the ship will bypass Kotor and proceed to Dubrovnik.  The ship will continue on her published schedule from Dubrovnik onwards.

We continue to work to re-route and re-accommodate air-sea guests to join the ship downline if possible.

Guests who disembarked in Venice are being looked after by our ground operations team. Air-sea guests have all been provided hotel accommodations courtesy of Regent Seven Seas Cruises and our team in Venice is doing everything within their power to provide assistance to all of our guests. We remain hopeful that the situation will improve in the coming days and will begin flying guests home as soon as the air traffic situation allows.

We will continue to provide updates as needed.