(Newser) – As if excrement-coated floors weren't outrageous enough, Quartz takes a look at another of Carnival Cruise's dirty secrets: Though it's exempt from a slew of taxes thanks to the fact that it's incorporated in Panama, it's gotten millions of dollars of assistance from the US Coast Guard in recent years. Sen. Jay Rockefeller last week sent a letter to Carnival's CEO in which he expressed his "serious concerns" about February's "nightmarish" Triumph stranding, and outlined how the Coast Guard and American taxpayer have continually had to come to the cruise line's rescue.

"In just the past five years I am aware of 90 serious events that have occurred on your cruise ships," he writes, before outlining the costs of just a few of them:

He asks: "Given that you reportedly pay little or nothing in federal taxes, do you intend to reimburse the Coast Guard and the Navy for the cost of responding" to the above? Rockefeller wants an answer by April 1. He's not the only senator who's peeved. Chuck Schumer today called for a cruise ship passenger bill of rights, akin to the one that exists for air travelers, reports CBS New York . Under it, ships would have to pledge to supply things such as backup power and sanitary conditions, and pony up full refunds if "failures" occur. (Read more Coast Guard stories.)