…it’s an incredibly silly question, I’ll grant you that without any argument.
I mean, it’s not like a dread War Galleon would even be able to get within grappling-hook range of the U.S.S. Nimitz…plus the fact that a carrier’s flight deck looks like it’s about 7 stories above the waterline…but I felt I should ask, just for curiosity’s sake.
AFAIK the last boarding of a vessel in wartime was when the crew of a US (maybe UK) destroyer boarded a German U-boat during WWII.
Not what you asked but I thought you´d like to know. 
It was the U-505, captured by boarding parties from the USS Guadlcanal.
Cite: http://www.msichicago.org/exhibit/U505/U505home.html
I don’t know if that was the last one, though.
Can you imagine the manpower needed to successfully board and capture a vessel with a crew of 6,200 ?
Wow.
Granted, most people on that vessel are probably unarmed, but I’m imagining that it would be a flipping bloodbath if you tried.
Fun facts:
Highest cruise liner capacity I could find with a quick googling was 3,840 passengers.
Even if you neglect the fact that the air power aboard the vessel could pound tar out of anything short of the Mighty Hand of God ™, and the defense provided by the 10-20 accompanying vessels in any carrier battle group… you have one final reason that it’d be nearly impossible to board her. The modern supercarriers have a confirmed top speed above 30 kts, and most likely could achieve about 42 kts. I’ll bet you next week’s pay that no naval vessel tall enough to board her without needing Batman’s grappling hooks could catch a modern supercarrier hell-bent on escape.
All naval vessels run security drills.
The threat with “boarders” isn’t cutlass-waving brigands on the high seas. It’s people of certain political persuasions looking to sabotage or vandalize naval vessels while anchored or moored.
You might be interested to know that a preferred method of repelling trespassers is by turning firehoses on them. Many firehoses on the weather decks are 2.5 inches in diameter. The force can knock a man down and even capsize a small boat.
It’s apparantly fun to watch Greenpeace members bounce.
The last combat boarding party I can recall was the Marines boarding the Mayaguez in May of 1975.