The Parcels ocean framework is an open-source Python library for building Lagrangian particle models (http://oceanparcels.org). It has been designed specifically for the purpose of combining (1) a large modularity to simulate the trajectory of different types of particles, from water to tracers and particulates such as plastic, algae or even fish, etc. and (2) an efficient implementation in accordance with modern computing infrastructure (Delandmeter et al., 2019, https://doi.org/10.5194/gmd-2018-339). The presentation will focus on Parcels design including a two-level Python-C dynamic structure and the new parallel routine to scale up with both increasing input data and number of particles.