A guarantee is a price, not a cabin
You book a category and the line picks the room — which deck, which end, which view — and it can pick it late. That is the trade, and whether it is a good one depends entirely on what the line's own terms permit it to assign you.
ScopeThe only guarantee terms worked up so far are Norwegian's — 10 hulls. Carnival and Celebrity Cruises and Royal Caribbean are charted for everything else and not for this, so nothing here should be applied to them. Guarantee terms differ by line and the differences are the whole question.
What you are actually agreeing to
The general shape, which is the part that does not vary.
A guarantee fare buys a category, not a room. The line assigns the specific cabin at its own convenience, and until it does, three things are genuinely unknown: the deck, the position fore and aft, and — depending on the line's terms — whether the view is obstructed.
Which means a guarantee is fine for a client who wants the lowest price and will sleep anywhere, and wrong for a client who is prone to seasickness, travelling with people they need to be near, or buying a balcony for the view. The saving is real; it is not free money. What it costs is every other cabin decision on this site.
No category codes appear on this page. The lines change them, and a stale code list is worse than none — that is the operator's call, recorded in the terms below.
What Norwegian actually permits
Recorded from the line's own terms, and signed. These are the sentences the ship reads carry.
On 6 hulls
Watch the guarantee categories on these ships. A guarantee means NCL picks the exact cabin, possibly as late as the day before embarkation, on any deck — and NCL's own terms say plainly that the room may be fully or partially obstructed, and that an oceanview guarantee can land as a porthole rather than a picture window. They're genuinely cheap and genuinely a gamble. If cabin position or the view matters to this client, the saving is not free money. I'm not giving you the category codes: NCL has been changing them, and a stale code list is worse than none.
On 4 hulls
NCL's own guarantee language warns that an assigned guarantee balcony may be fully or partially obstructed. That's the line saying in its own terms that a guarantee category does not protect the view — so if the client cares about what they'll see, pick the cabin rather than taking the guarantee rate.
The lines this page cannot speak for
Charted for cabins, money and traps — and not for this.
Carnival and Celebrity Cruises and Royal Caribbean have no guarantee terms on record.
That is a gap in what we have looked at, not a clean bill of health. Check this part of the booking the way you would without CruiseRead.
Do not carry the terms above across. Whether an assigned guarantee can land obstructed, how late it can be assigned and what an oceanview guarantee is permitted to become are all line-specific, and reading one line's answer onto another is the exact error this site is built to stop.
If the cabin matters, don't guarantee it
And if you are going to, run the booking first so you know what you are gambling.
A guarantee gives away the placement call, which on most hulls is the single most consequential thing an advisor gets to decide. Read what a quiet cabin actually requires and what an obstructed balcony can mean before deciding the saving is worth it — those are the two things a guarantee is putting on the table.