There is indeed a principle that if Mass is not available while traveling, the obligation to attend Mass is dispensed. But there is also the principle that our Lord is worth standing up for, even at great personal sacrifice, since he sacrificed his very life for us. If you continue to cruise with a cruise line that chooses to cut necessary pastoral care for Catholics who are spending a great deal of money to travel on their ships, then you tell the cruise line through your actions that you are perfectly fine with their decision to do this. If, instead, you let the company know that the loss of money and pleasure travel matters less to you than your Catholic faith, perhaps they might be put on notice that their decision will mean that Catholics will no longer be contributing to their “bottom line” (which makes a difference in a bad economy in which the luxury industry suffers first). In sum, you are free to go on this cruise if you want, but it might be more appropriate to consider taking a principled stand for your Lord, your faith, and your fellow Catholics, and cancelling the cruise. Perhaps you might consider doing so your Lenten sacrifice this year.