Deal watch: Luxury cruises on sale at Silversea

It's deal time for one of the world's most luxurious cruise lines.

Silversea Cruises on Tuesday kicked off a month-long promotion that brings an on-board spending credit of $500 to $1,000 per room on select 2015 sailings.

The Silver Wave offer, as it's being called, also includes a free upgrade. It's available with 31 sailings around the globe. Bookings must be made by Dec. 31.

The available voyages include a nine-night Bali to Singapore sailing departing on Jan. 15 and an 11-night Singapore to Hong Kong sailing departing on Feb. 27 — both on the 296-passenger Silver Wind. Fares for the trips start at $4,250 per person.

Also part of the offer is a 12-night sailing on the 296-passenger Silver Cloud from Copenhagen to London. Fares for the trip start at $6,850.

All three of the above sailings come with a $1,000 per room spending credit as do two trans-oceanic cruises included in the promotion.

The other 26 voyages that are part of the deal come with a $500 spending credit. They include three sailings in Alaska, two sailings along Australia's Kimberley coast, two sailings in the Caribbean and two sailings in the Mediterranean.

More information about the offer is available at Silversea's website.

For a deck-by-deck look at a Silversea ship, click through the carousel at the top of the story.