<p>The Isthmus of Panama experiences high seismic activity, having the potential for destructive earthquakes and serious risks to the population. Here, we present a new 1-D P-wave velocity model for Panama, which could be used for routine and accurate determination of earthquake locations, since Panama currently relies on a global velocity model. We used 23,178 P-wave arrival times from 1,672 selected seismic events between 2013 and 2022, recorded by 128 seismic stations across the country. To perform the analysis of P-wave arrival times, we utilized the Particle Swarm Optimization (PSO) method, which propagates multiple particles that explore the solution space to find the best possible velocity model. The new 1-D P-wave velocity model was obtained after multiple PSO runs, using the results of the previous run as a starting model until we find a model that best fits the seismic data. This model consists of 10 layers extending to a depth of 70 km, where the velocities range from 5.76 km/s at depths of 0-5 km to 8.27 km/s in the deepest layer. The station corrections, consistent with the geology of the Isthmus, allowed accurate relocation of earthquakes, achieving an epicentral distance error of ±3 km and a hypocentral distance error of ±6 km. These results are not only relevant for 3-D seismic tomography, but also valuable for seismic hazard and risk assessments in the Isthmus of Panama.</p>