How we test and rank

Prices last confirmed September 2026

1. Coverage type comes first

Before price, before data allowance, we establish whether a plan works in open water. A plan qualifies as 🟢 works at sea only if the provider states at-sea or maritime network coverage and names the vessels or operators it covers. Cruise-themed branding is not evidence: several “[Region] Cruise eSIM” products are terrestrial, as are Yesim’s cruise landing pages, and we label them accordingly.

A plan that does not work at sea can never outrank one that does for sea-day use, no matter how cheap it is. That rule is not overridable by any commercial relationship.

2. How coverage is classified, exactly

Every plan lands in one of four buckets, and the rule is mechanical rather than editorial so that it cannot drift with whoever writes the page:

• 🟢 Works at sea + ports — an at-sea plan whose name joins the cruise product to a land scope. That is the vendors’ own naming convention: Cruise + Europe, Cruise + Americas/Caribbean, Global + Cruise Unlimited. One purchase covers the whole sailing.
• 🟢 At sea only — an at-sea plan with no land scope, or one whose own activation terms say it does not connect in port. Saily Cruise and eSIM.dog Cruise are both in this bucket, and both need a second eSIM for shore days.
• 🟡 Ports & land only — everything else, regardless of what it is called. A plan branded “[Region] Cruise eSIM” that runs on land networks gets this label and a sentence saying it goes dark at sea.
• 🔵 Ferry — an operator-branded plan for a specific crossing.

The upstream network is recorded per plan and published on the networks guide, including where a provider declines to state it.

Cruise-themed branding is never evidence of at-sea coverage. The detection sources, in order: the provider’s own product name and published activation terms, then their vessel or operator list, then their support documentation. If none of the three states maritime coverage, the plan is port-only here no matter how it is marketed.

3. Effective cost per gigabyte, and the unlimited rule

Value is ranked on price ÷ gigabytes, not on headline price — a $14.49 plan with 100 MB on it is the most expensive data on this site, and a ranking that sorted on the sticker would put it first.

Unlimited plans have no gigabyte figure, so we impute 20 GB per 30 days, pro-rated by validity. A 7-day unlimited plan therefore counts as about 4.7 GB, and a 3-day one as about 2 GB. That figure reflects what heavy travellers actually consume on a metered plan; applying it consistently is what lets an unlimited plan and a 5 GB plan sit on the same axis at all. It is an assumption, it is stated here rather than hidden, and it is the same number for every provider.

Two rows are excluded from value ranking rather than being given a misleading score: free trials, which would otherwise rank first at $0.00/GB forever, and plans priced in a currency other than USD. We do not convert those — converting means inventing an exchange rate and publishing it as the provider’s price.

4. What the nightly job does, and why most catalogues yield nothing

A scheduled job pulls the provider catalogues we have API access to and filters every row against the cruise/ferry test before anything is written. Most catalogues yield zero rows, and that is the correct result rather than a fault. A general travel eSIM provider selling four thousand country and regional plans has no maritime product in any of them, so nothing from that feed belongs in a database of cruise plans.

The consequence is a database that is small on purpose. Ingesting the ordinary plans would make the catalogue look impressive and make every comparison on the site useless, because the reader would have to work out which of four thousand plans survives past the coastline — which is the job they came here to have done for them.

Coupons are re-checked against a live checkout rather than copied from other sites, and each one carries the date it was last confirmed. A code that fails verification is removed rather than left up with an older date — a dead coupon with a fresh-looking date is worse than no coupon page at all.

5. Where the numbers come from

Plan prices come from provider catalogs and partner APIs, refreshed on a schedule, with a seeded baseline for anything not yet automated. Every row carries the date it was last confirmed and a re-verification deadline; rows past their deadline are flagged internally for a human check. Where a price is our estimate rather than a captured figure — currently some Maya and GigSky regional tiers — the plan says “estimated price” on its own card.

Ship Wi-Fi prices are captured per cruise line and re-checked quarterly. Lines whose figures are estimates say so in their Wi-Fi notes.

6. Ship coverage claims

We report vessel coverage as the provider states it (GigSky: 290+ ships; Saily: 28 cruise and ferry operators across 28 operators) rather than independently auditing every hull, because no consumer can verify that and pretending otherwise would be dishonest. What we do verify is the shape of the product: whether it covers port as well as sea, whether it activates only beyond 12 nautical miles, and whether a free trial exists.

7. Our GigSky partnership, stated plainly

GigSky is our flagship partner. It appears first in plan listings, has a dedicated hero placement, and our exclusive ESIMDUDE code carries a 10% discount. That is a commercial relationship and you should read our recommendation with it in mind.

Here is how we stop it distorting the facts:

• The Cheapest sort tab ignores partnership entirely and ranks purely on effective cost per GB. Saily currently leads it, and we say so.
• Every GigSky recommendation states where it loses — it is not the cheapest per gigabyte, and it is redundant spend if you already carry a regional eSIM.
• Rival plans are never hidden, downranked below their value, or described inaccurately.
• Where ship Wi-Fi or an included fare perk beats every eSIM — transatlantic crossings, Princess Plus, Virgin Voyages, Viking — we recommend that instead.

The justification for the placement is factual and checkable: GigSky has the widest ship list, covers both sea and port on one SKU (as do Maya and OneRoam, on shorter ship lists), is the only source of ferry-branded plans, and is the only provider offering a free trial. If those facts change, the placement changes.

8. Corrections, and the log

If a price, coupon or coverage claim here is wrong, tell us and we will fix it and re-date the page. Reader corrections outrank provider marketing every time.

Corrections are recorded here rather than quietly edited away. A comparison site that silently rewrites its errors is asking for trust it has not earned, and the useful part of a correction is usually the change that stops it recurring rather than the apology.

This log starts from the date the site launched and lists material errors — a wrong fact, a wrong price, or a claim we could not support — not typos or layout fixes.

Prices last confirmed September 2026.