Background: Much previous research has used apneic face immersion as a model for studying the diving response and its oxygen-conserving effect, however there are few direct comparisons to apneic face immersion with the body immersed. Therefore, it is not settled if the oxygen conserving effect revealed in the dry-body model persists in the immersed diver. In this study we compared the diving response and its effect on arterial oxygen saturation between apnea in horizontal dry-body and immersed-body conditions. Methods: Twelve individually determined near-maximal apneas of the same duration were completed by 17 healthy untrained subjects at rest. Three apneas in each of four categories were performed: dry-body apnea (DA), dry-body, face-immersion apnea (DFIA), immersed-body apnea (IA), and immersed-body, face-immersion apnea (IFIA), in a weighted order. For the face and body immersions, mean water temperature (± SD) was 23.1 ±0.12oC and mean air temperature was 23.3 ±0.32oC. Heart rate and arterial haemoglobin saturation were recorded non-invasively with a pulse oximeter. Results: The diving response was similar for both the dry-body and the immersed body-categories. In all 4 categories the heart rate was reduced. The heart rate reduction in DFIA and IFIA categories was more pronounced than in the DA and IA categories. Heart rate reduction during DA and DFIA was 10% (±1.6) and 18% (±2.8) respectively (P<0.01), while heart rate reduction during IA and IFIA was 9% (±2.6) and 18% (±3.1) respectively (P<0.01). In both the DFIA and IFIA categories there was less desaturation compared to the DA and IA categories (DA vs. DFIA P<0.001, IA vs. IFIA P<0.05). Conclusion: Face immersion enhances the apneic diving response both in the dry- and immersed-body conditions, and is associated with a less pronounced arterial oxygen desaturation. We conclude that the immersed diver may benefit from an oxygen conserving diving response. This study also shows that the dry-body model can be useful for studying the diving response.