We investigate the contribution of oceanic methyl iodide (CH<sub>3</sub>I) to the stratospheric iodine budget. Based on CH<sub>3</sub>I measurements from three tropical ship campaigns and the Lagrangian transport model FLEXPART, we provide a detailed analysis of CH<sub>3</sub>I transport from the ocean surface to the cold point in the upper tropical tropopause layer (TTL). While average oceanic emissions differ by less than 50% from campaign to campaign, the measurements show much stronger variations within each campaign. A positive correlation between the oceanic CH<sub>3</sub>I emissions and the efficiency of CH<sub>3</sub>I troposphere–stratosphere transport has been identified for some cruise sections. The mechanism of strong horizontal surface winds triggering large emissions on the one hand and being associated with tropical convective systems, such as developing typhoons, on the other hand, could explain the identified correlations. As a result of the simultaneous occurrence of large CH<sub>3</sub>I emissions and strong vertical uplift, localized maximum mixing ratios of 0.6 ppt CH<sub>3</sub>I at the cold point have been determined for observed peak emissions during the SHIVA (Stratospheric Ozone: Halogen Impacts in a Varying Atmosphere)-Sonne research vessel campaign in the coastal western Pacific. The other two campaigns give considerably smaller maxima of 0.1 ppt CH<sub>3</sub>I in the open western Pacific and 0.03 ppt in the coastal eastern Atlantic. In order to assess the representativeness of the large local mixing ratios, we use climatological emission scenarios to derive global upper air estimates of CH<sub>3</sub>I abundances. The model results are compared with available upper air measurements, including data from the recent ATTREX and HIPPO2 aircraft campaigns. In the eastern Pacific region, the location of the available measurement campaigns in the upper TTL, the comparisons give a good agreement, indicating that around 0.01 to 0.02 ppt of CH<sub>3</sub>I enter the stratosphere. However, other tropical regions that are subject to stronger convective activity show larger CH<sub>3</sub>I entrainment, e.g., 0.08 ppt in the western Pacific. Overall our model results give a tropical contribution of 0.04 ppt CH<sub>3</sub>I to the stratospheric iodine budget. The strong variations in the geographical distribution of CH<sub>3</sub>I entrainment suggest that currently available upper air measurements are not representative of global estimates and further campaigns will be necessary in order to better understand the CH<sub>3</sub>I contribution to stratospheric iodine.