This is the M5 super yacht and it is currently anchored in Drew Harbour on Quadra Island.
It is the largest single-masted yacht ever built and it is valued at over $50 million.
Yes, that is a float plane sitting on the back of the boat.

More information (and better photos) can be found here:
https://www.boatinternational.com/yachts/editorial-features/sailing-yacht-m5

Like many other Quadra Islanders I was intrigued by this visitor.
It is impressive as an engineering feat, but also appalling as a
symbol of the growing inequality in much of the world.

Best viewed at original size.