This is absolutely insane. Apparently, there are people so rich that, not happy with having their own megayacht, get themselves a huge support ship to carry giant speedboats, sailboats, helicopters and even submarines. That's what the Sea Axe is.
The Sea Axe comes in 37m, 51m or 67m flavours, and it's capable of carrying other ships, fuel and supplies. It has transatlantic range and can travel at a top speed of 28 knots. [James List]