Systems and methods for navigating a catheter along the epieardial surface of the heart are disclosed. At least some of the embodiments disclosed herein are useful for epieardial ablation, Various embodiments permit ablation of the epieardial surface of the heart using an external ablation catheter in the pericardial space and an internal guide catheter within the heart. Such a configuration allows the clinician to precisely target for ablation specific locations on the cardiac tissue.