The master suite of 66.4 metre ISA motor yacht Okto, designed by the late Alberto Pinto, is a great place to chill out. Even with balcony doors open, cooler air stays inside thanks to an air-curtain barrier, which also helps keep bugs out too.
There's even a technical solution for slotting in the guardrails that doesn't require the crew – simply push a button and they fold up out of the balcony.