December splits cleanly in two. The first three weeks are one of the year's best-value windows almost everywhere; Christmas and New Year sailings are the most expensive of the year and sell out a year ahead. Book the season, not the holiday, unless the holiday is the point.
Caribbean: early-month value, holiday peak
Early-to-mid December delivers the Caribbean at 26–29°C with dry-season weather settling in and fares at $700–1,100 for seven nights. Christmas week jumps to $1,200–1,800 and books out months ahead. Eastern Caribbean routes run at full frequency.
Antarctica: penguin chicks and peak season
December is Antarctica's busiest and most wildlife-rich month: penguin chicks hatch, days stretch to 20+ hours of light, temperatures peak at -2 to +4°C. Ten-to-fourteen-day voyages run $8,000–15,000. Antarctica: what it really involves sets expectations; the South America and Antarctica route is the reference sailing.
Rhine: Christmas markets
Early December is Europe's river-cruise finale: Germany's Christmas markets glow along the Rhine (germany.travel dates the official market season from late November, most markets closing just before Christmas), ships are decked for the season, and week-long fares run $1,200–2,000. It is cold — 0–6°C — and magical. The Rhine river route is the classic; most sailings end before Christmas week.
Australia and New Zealand: summer arrives
December opens the southern summer: Sydney to Auckland routes run at 20–27°C with long evenings. Thirteen-day fares run $1,100–1,900, rising over the holidays. The Australia and New Zealand route covers both coasts.
Southeast Asia: dry season in full swing
The region's best cruising weather: 25–31°C, low rain, calm seas. Twelve-night fares run $900–1,600, spiking over Christmas and New Year. The Singapore to Bangkok route sails at full schedule.
The five-minute version
- Caribbean: early month $700–1,100; Christmas week $1,200–1,800, book far ahead.
- Antarctica: peak season, chicks hatching, $8,000–15,000.
- Rhine: Christmas markets early month, $1,200–2,000, cold and magical.
- Australia and New Zealand: summer opens, $1,100–1,900.
- Southeast Asia: best weather of the year, $900–1,600.