If you’ve ever booked a sea freight shipment, you know that packaging isn’t just about throwing your goods in a box and crossing your fingers—especially when that shipment is crossing oceans. I’ve been running a sea freight operation for 12 years now, and I can’t tell you how many times I’ve pulled a container off a ship that arrived looking like it had been through a hurricane, only to find that a simple packaging mistake was the root cause. Last year, we had a client ship custom ceramic bathroom fixtures from Guangzhou to Los Angeles; they used thin cardboard boxes wrapped in cheap stretch wrap, and by the time the ship docked, 30% of the pieces were cracked. The sad part? It could’ve been fixed with a $15 upgrade in packaging materials. That’s why I’m putting together this guide today—based on what I’ve seen work, what fails, and what our team at the freight yard consistently recommends to avoid the kind of headaches that come with ocean shipping. Sea Freight
First, let’s break down why sea freight packaging is so different from air or ground. Ocean transit is a marathon, not a sprint. A standard route from Shanghai to Hamburg takes around 42 days, longer if there are port delays, reroutes, or seasonal slowdowns. During that time, a container is stacked 10-high on a cargo ship, exposed to constant vibration from the engine and rough seas, swings of humidity that can warp wood or rust metal, and temperature fluctuations that range from sweltering in the sun to near-freezing at night. There’s also the handling: a single container might be moved 8 to 12 times between factories, ports, trucks, and trains before it reaches its final destination. Cheap packaging might hold up to a single truck ride, but it won’t survive that kind of journey.
Let’s start with the most basic (and most versatile) packaging: corrugated fiberboard, but not just any corrugated. I can’t tell you how many times a shipper walks in with a box marked “50 lbs maximum” and tries to pack 75 lbs of goods into it—bad move. For sea freight, you need to use double-wall corrugated boxes, minimum 32 ECT (edge crush test) rating. That rating is non-negotiable; ECT measures how much force a box can take along its edge, and 32 ECT means it can hold up to 65 lbs without collapsing. For heavier items, go for triple-wall corrugated, which can handle 120 lbs or more. We had a client ship small auto parts from Mexico to Houston last month; they used standard 20 ECT boxes, and half the boxes crushed in the middle of the container, spilling nuts and bolts all over other shipments. Switched them to 32 ECT double-wall, and they haven’t had a problem since. Another pro tip: choose boxes with interlocking flaps, not adhesive-only flaps. Adhesive can fail from humidity during ocean transit, but interlocking flaps stay closed even if the tape comes loose. Also, never use boxes that are too big for your goods. Empty space inside a box leads to shifting, which damages goods, and also wastes space in the container—costing you more money. If you have leftover space, fill it with void fill, not loose packing peanuts (more on that later).
Next up, wood packaging, because sometimes corrugated just isn’t strong enough. But here’s the thing about wood for sea freight: not all wood is allowed. International phytosanitary rules—known as ISPM 15—require all raw wood used for packaging (pallets, crates, dunnage) to be heat-treated or fumigated to kill pests like termites that could hitch a ride across oceans. Ignore that rule, and your entire shipment can be held at customs, delayed for weeks, or even sent back. I’ve seen it happen: a small business owner from Indiana tried to ship custom wooden furniture to Sydney with untreated pallets, and Australia’s biosecurity team refused to unload the container. They had to burn the pallets at the port, pay a $1,200 fine, and re-palletize the furniture on-site with ISPM 15 compliant pallets. It was a $5,000 mistake that could’ve been avoided with a $30 pallet upgrade. So if you’re using wood, always look for the ISPM 15 stamp— it’s a simple mark on the side of the pallet or crate with letters that say HT (heat-treated) or MB (methyl bromide fumigated). For heavy, fragile, or irregularly shaped goods—like industrial machinery, artwork, or oversized parts—custom wooden crates are the way to go. Unlike standard pallets, crates are built to fully enclose and protect your item, and they can be reinforced with metal corner protectors or straps for extra sturdiness. We work with a local crate builder that’s been in business for 20 years, and we always refer clients to them because they build crates specifically for ocean transit, not just ground.
Now, flexible packaging, which is perfect for non-fragile, bulk goods like textiles, plastic parts, or food products. The most common type for sea freight is woven polypropylene (PP) bags. These are stronger than plastic bags, water-resistant, and can hold heavy loads—up to 2,000 lbs per bag, depending on the grade. If you’re shipping food products, make sure the bags are food-grade, to avoid contamination. Another flexible option is bulk flexible intermediate bulk containers (FIBCs), also known as “bulk bags.” These are large, reusable bags that hold 1,000 to 2,000 lbs of granular or powdered goods, like grains, cement, or chemicals. They’re designed to be lifted by forklifts, and they fit perfectly in standard sea containers to maximize space. One thing to watch with flexible packaging: humidity. If you’re shipping goods that can absorb moisture, like cotton or raw sugar, make sure the bags are lined with a polyethylene (PE) film to keep water out. I learned this the hard way a few years back when a client shipped raw coffee beans from Colombia to Rotterdam in unlined PP bags. The container got caught in a storm, and seawater seeped through the bag material, ruining 10 tons of beans. Now we always remind clients to line flexible packaging with a moisture barrier when shipping any hygroscopic goods.
Then there’s void fill and protective padding, the unsung heroes of sea freight packaging. Even if you have the sturdiest box or crate, shifting during transit will damage your goods if there’s empty space. For that, avoid packing peanuts—they generate static electricity, can leave residue on goods, and often shift over time. Instead, use air pillows, which are lightweight, take up almost no space until you inflate them, and are perfect for filling gaps. Or use corrugated fillers, which are made from recycled cardboard, strong, and can be cut to fit any size gap. For fragile items—glass, electronics, porcelain—you’ll need more than just void fill. Bubble wrap is common, but go for anti-static bubble wrap if you’re shipping electronics, to avoid damage from static. For extra fragile goods, like artwork or medical equipment, use foam padding, specifically cross-linked polyethylene (XLPE) foam, which is denser than regular foam, water-resistant, and absorbs shock way better. We recently shipped a batch of MRI machines from Berlin to Seoul; each machine was wrapped in XLPE foam, then put in a custom wooden crate lined with foam, and none of them had a single scratch, even after a 6-week transit. That’s the kind of protection you need for high-value, fragile goods.
Wait, I should also talk about what to avoid. First, single-use plastic wrap for large shipments. It’s not strong enough to hold multiple boxes together through the rough handling of sea freight, and it can tear easily, leaving boxes loose and at risk of falling off pallets. Second, untreated wood, like I mentioned earlier. The fines and delays aren’t worth the risk. Third, overpacking. Even though you want your goods to be safe, stuffing a box so full that it can’t close leads to burst flaps and broken items. Fourth, using low-quality tape. Not just any packing tape will do for ocean shipping. Go for high-strength, pressure-activated tape, at least 2.6 mils thick. Regular cellophane tape or masking tape will peel off from humidity or vibration in days. We stock the good stuff at our freight yard, and we always recommend our clients pick it up when they drop off their goods.
Another thing I can’t emphasize enough: labeling and documentation, which go hand in hand with packaging. Your packaging should be clearly labeled with your company name, the destination address, and any handling instructions—like “fragile,” “this side up,” or “keep dry.” Use waterproof labels, not paper ones that will smudge or fall off if exposed to water. And make sure all documentation—like the bill of lading, customs forms, and any phytosanitary certificates—are securely attached to the outside of the shipment, in a waterproof document pouch. I’ve had shipments where the label fell off, and we had to trace the container across three ports to find the right one—costing the client an extra $800 in storage fees and delays. Don’t let that happen to you.
Let me wrap this up with a quick case study to show you how all this works together. Last quarter, we had a client that specializes in exporting custom outdoor furniture from Portland to Tokyo. Their previous packaging was thin corrugated boxes on untreated pallets, and they had 15% damage on each shipment. We worked with them to switch to double-wall 32 ECT corrugated boxes, custom ISPM 15 heat-treated pallets, and each piece of furniture was wrapped in XLPE foam and air pillows inside the boxes. We also added “keep dry” labels and a waterproof document pouch. Their next shipment had less than 1% damage, and they saved 10% on shipping costs because the sturdier packaging let them stack boxes higher in the container. That’s the kind of result we strive for every day here at our sea freight operation.
If you’re planning a sea freight shipment and you’re not sure what packaging is right for your goods, don’t guess. I’ve seen too many small business owners and first-time shippers lose money because they tried to cut corners on packaging. Our team has over a decade of experience working with all kinds of goods, from industrial machinery to consumer goods, and we can help you pick the right materials to keep your shipment safe, on time, and within budget. We also offer packaging consulting at our yard, so you can drop off your goods, and our team will help you pack them properly, no hidden fees. If you’re ready to book a shipment or just have questions about packaging for sea freight, get in touch with our team to discuss your specific needs. We’re here to make your ocean shipping experience as smooth as possible, because when your goods arrive on time and in perfect condition, that’s when our job is done right.
Sea Freight REFERENCES
- International Plant Protection Convention (IPPC). ISPM 15: Regulation of Wood Packaging Material in International Trade. 2019.
- Sea Freight Packaging Best Practices. International Association of Movers (IAM). 2022.
- Edge Crush Test (ECT) Standards for Corrugated Packaging. American Society for Testing and Materials (ASTM) D7807-18. 2018.
- Packaging for Ocean Transit: Risk Mitigation Guide. Global Logistics Association (GLA). 2021.
Shenzhen Senghor Sea & Air Logistics Co., Ltd.
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