7 Mistakes That Ruin Thailand Liveaboard Trips (and How to Dodge Them)

The Trip You Paid $1,500 For Can Still Go Wrong

Thailand liveaboards look interchangeable from a booking page. Same price range, same dive count, same stock photos of whale sharks. They are not interchangeable, and the difference between a great week and a miserable one usually comes down to five or six decisions you made weeks before the boat left the pier. Most of those decisions are reversible if you catch them before you pay the deposit.

These are the mistakes we watch divers make over and over. None of them are about being a bad diver. They are about not knowing what to ask.

Mistake 1: Booking the Wrong Boat Size

Operators know "liveaboard" sells better than "boat with 22 strangers on it." A lot of the cheaper 5D/4N deals are boats running 20+ guests with two or three guides. That puts you at a 1:8 or 1:10 guide-to-diver ratio, which means rushed briefings, longer waits between drops, and a group that gets spread thin on any site with current.

The number to push for is 1:4 to 1:6. On a 12-guest boat with three guides you will almost always be on the correct side of that range. On an 18-guest boat, confirm the guide count before you pay. If the operator dodges the question, that is your answer.

Mistake 2: Booking the Wrong Month

Similan Islands, Surin, and Mu Ko Lanta close mid-May through late October for the southwest monsoon. The parks are physically shut. If you book a Similan liveaboard in September thinking you got a bargain, you will get a cancellation email a week before departure or a forced itinerary change to the Gulf of Thailand, which is a different country as far as diving goes.

The real window for Andaman liveaboards is November through April, with December-March being the sweet spot for visibility and whale shark sightings at Richelieu Rock. May is a coin flip. Book the shoulder months only if your cancellation policy is ironclad.

Mistake 3: Ignoring the Cancellation Policy

Standard Thai liveaboard policies look like this: full refund if you cancel 60-90 days out, 50% at 30 days, nothing inside 14 days. Deposits are usually 20-50% of the total, which translates to $300-800 on a 6-7 night Similan trip. Luxury boats demand more upfront.

Before you pay, read what happens if the operator cancels versus if you cancel. If a typhoon wipes out your week, do you get a refund, a credit, or a rescheduled date? What if Similan closes early? Operators with reputations fold on this fast. Operators chasing bookings write the policy in their favor and stick to it.

Mistake 4: Not Checking What's Actually Included

The headline price on a Thailand liveaboard rarely includes everything. The usual line items that get added at the pier: national park fees ($100-150 for Similan and Richelieu combined), gear rental if you don't bring your own, Nitrox upgrades on boats that charge for them, and Myanmar permits (~$200) if the trip crosses into Mergui.

Ask the operator for a written list of what is included and what is extra before you pay the deposit. Budget another 15-20% on top of the headline for the pier charges and crew tips. A $1,200 boat becomes $1,500 real quick, and that math is fine if you expected it — brutal if you didn't.

Mistake 5: Underestimating Seasickness

The Andaman in December is calm. The Andaman in a November northeast wind is not. The southern routes to Hin Daeng sit in more open water than the northern Similan route, and the Mergui crossing from Ranong is the roughest of the three. Divers who get seasick on day-trip boats and book a 5-night liveaboard hoping they will "get over it" usually do not.

If you have any history of motion sickness, choose the northern Andaman route, book a larger boat (more guests = bigger hull = less roll), take your meds before symptoms start, and ask for a lower-deck cabin closer to the centerline. Scopolamine patches work better than oral meds for multi-day trips.

Mistake 6: Skipping the Check Dive

Every reputable Thailand liveaboard runs a check dive at an easy site before the real itinerary starts. It exists so guides can see your buoyancy and sort groups. Some divers treat it as optional or rush through it to get to the "good" sites. A boat that lets you skip the check dive is a boat that will put you in a mixed-ability group at Koh Bon where the current is ripping.

Do the check dive. Nail the buoyancy. Let the guide see you work. You will get put in the right group, and the rest of the week gets better. This is not a box-ticking exercise — it is how operators match you to sites that actually fit your skill level.

Mistake 7: Booking Through the Wrong Channel

Cross-check PADI or SSI operator ratings before you wire money. Read 2025-2026 reviews on TripAdvisor and DiveReport, not just what is on the operator's own site. Aggregators like LiveAboard.com hold your payment in escrow, which matters if the boat pulls out of service mid-season. Booking directly with a reputable local shop is usually the cheapest option, but only if you can verify they actually exist — ask for a Thai business registration, not just a logo.

Red flags: operators who will not confirm the guide count, boats with no recent reviews, deposits demanded over Western Union, and itineraries that sound like they cover three regions in four days.

Book It Through SiamDive Without the Guesswork

We operate inside Thailand and vet every boat we sell on the water — not off a brochure. If you send us your experience level, budget, and travel dates, we match you to a trip where the boat size, guide ratio, route, and season actually line up. Skip the research spiral. Check current departures at siamdive.com.