Question on clearing Customs enroute to Sydney

In less than two weeks we will be traveling from Dallas to Sydney via:

DFW-LAX on United

LAX-ICN (Inchon) on Asiana

ICN-BKK (Bangkok) on Thai Airways

BKK-SYD on Thai Airways

We have layovers in LAX, ICN and BKK but will not be leaving the airports.

When we arrive at ICN will we need to clear our luggage at Customs and then recheck it in with Thai? Or since we are only transiting the country and not leaving the airport, will our bags be checked all the way through to SYD without clearing Customs until we arrive there?

Assuming this trip is booked on one ticket regardless of multiple carriers you will check in your bags and not see them again until you get off in Sydney as they will be considered in transit. If the flight were booked under two tickets you would have to collect your bags when the first ticket ended and then go through the check in process on the second ticket.

Assuming this is all ONE ticket, and not some combination of tickets pieced together:

You will not need to clear any form of immigration at ICN or BKK, nor any customs processing. You will have a security screening at both ICN and BKK post-arrival and before heading to your onward gate.

If you are interested, and have a long connect at ICN, there are tours available to Seoul, ranging from 1 to 6 hours. If you take those tours, they can provide storage for your carry-ons, however you need to go through immigration and fill out a customs form. You do not process your checked bags, as they continue on to BKK. Cost for the tours ranges from $1 to $10, with the more expensive/longer ones including a meal. Basically, the tour is free, they cost is to pay for any entrance fee to a shrine/site and any meal provided. IIRC, there are at least six different tours offered, leaving at different times in the day. I can research more if requested, as I have the brochure available in some files.

Thank you! The travel agent who handled the cruise arrangements said I would need to claim my bags at ICN but that didn't sound right since I'm traveling on one ticket.

Assuming this is all ONE ticket, and not some combination of tickets pieced together:

 

You will not need to clear any form of immigration at ICN or BKK, nor any customs processing. You will have a security screening at both ICN and BKK post-arrival and before heading to your onward gate.

 

If you are interested, and have a long connect at ICN, there are tours available to Seoul, ranging from 1 to 6 hours. If you take those tours, they can provide storage for your carry-ons, however you need to go through immigration and fill out a customs form. You do not process your checked bags, as they continue on to BKK. Cost for the tours ranges from $1 to $10, with the more expensive/longer ones including a meal. Basically, the tour is free, they cost is to pay for any entrance fee to a shrine/site and any meal provided. IIRC, there are at least six different tours offered, leaving at different times in the day. I can research more if requested, as I have the brochure available in some files.

Thanks for the suggestion. Our return routing is SYD-ICN-LAX-DFW, skipping BKK, but we have a 22 hour layover in ICN. We have a hotel reservation for the evening and a late afternoon departure to LAX, so we'll take the train from ICN to downtown Seoul and do the tourist thingie.