For the first time, a comprehensive study of sorbents based on manganese dioxide was carried out for beryllium sorption from seawater in laboratory and expeditionary conditions. The possibility of using several commercially available sorbents based on manganese dioxide (Modix, MDM, DMM, PAN-MnO2) and phosphorus(V) oxide (PD) for 7Be recovery from seawater for solving oceanological problems was evaluated. Beryllium sorption under static and dynamic conditions was studied. The distribution coefficients and dynamic and total dynamic exchange capacities were determined. Sorbents Modix (Kd = (2.2 ± 0.1) × 103 mL/g) and MDM (Kd = (2.4 ± 0.2) × 103 mL/g) showed high efficiency. The dependences of the degree of recovery on time (kinetics) and the capacity of the sorbent on the beryllium equilibrium concentration in solution (isotherm) were established. The data obtained were processed using kinetic models (intraparticle diffusion, pseudo-first and pseudo-second orders, Elovich model) and sorption isotherm equations (Langmuir, Freindlich, Dubinin-Radushkevich). The paper contains results of expeditionary studies to evaluate the sorption efficiency of 7Be from large volumes of the Black Sea water by various sorbents. We also compared the sorption efficiency of 7Be for the considered sorbents with aluminum oxide and previously obtained sorbents based on iron(III) hydroxide.