Several recent articles have used modeling results to calculate sea salt or sulfur exchange between the atmosphere and oceans. In all cases, modeling uncertainty for small-particle dry deposition is grossly underestimated. This short note discusses the magnitude of uncertainty that presently pervades these modeling results. The conclusion, based on a review of models and the limited experimental data available, is that the uncertainty in small-particle (diameter D<1 μm) dry deposition to water surfaces is about two orders of magnitude. It is suggested that future calculations of small-particle atmosphere-ocean exchange account for this ⊥1 order of magnitude unccertainty and that direct open-ocean measurements are needed before any reduced uncertainty may be expected.