Prioritise WMS/API integration, inventory accuracy, order cycle time, OTIF, dock‑to‑stock speed, racking density, ambient vs. climate‑controlled bays, throughput capacity during peaks, and carrier connectivity to mainland hubs. Verify SLA penalties, reporting cadence, and contingency plans for ferry disruptions.

Ferry frequency adds deterministic transfer windows that affect cut‑off times and daily departures. Consolidating shipments to mainland hubs can reduce per‑unit costs but adds a scheduled transfer step. Select carriers and 3PLs with established transfer processes and buffer strategies to manage variability and maintain predictable delivery windows.

Require real‑time WMS connectivity (APIs/EDI), order management for multi‑channel routing, returns processing, kitting/assembly, barcode scanning, automated picking options, and standardized reporting. Ensure the provider can scale resources seasonally and demonstrate integration with your marketplace and carrier ecosystems.

Customs clearance, duty accounting, and export documentation are typically handled via mainland brokers or bonded facilities; factor in transit windows to and from ports, potential ferry surcharges, and the 3PL’s customs brokerage capability. Request landed‑cost scenarios and bonded options if you move international freight regularly.