13 of 55 destinations scored for swimming are prime in December — 80 or better on conditions alone. Highest: Oman (92), Guanacaste & Tamarindo (91), Turks & Caicos (90). In November 2 are prime; in January, 17.
Every destination scoring 55 or better for swimming in December, highest first. Ties are listed alphabetically.
Most places have one or two months that are genuinely better — and a booking moment that comes a lot earlier than the trip. I’ll write when one of those is coming up. No schedule, no filler.
Somewhere missing from the list? Write to info@pennyswindow.com and I’ll score it.