User Recommendations for Black Lagoon

If you liked Black Lagoon, you may like Full Metal Panic! Both series are action-filled and involve mercenaries and are based from a naval unit. Black Lagoon is a bit darker, more bloody, more philosophical, and a bit more personal in the fights while Full Metal Panic! has more humor and silly episodes. However, when the action starts for Full Metal Panic! and the bullets start flying and people start dying you'll enjoy this series as well. There's mech sliding, grenade throwing, RPG lauching, booby traps setting, hostage taking, body-guarding, character kidnapping, submarine diving, ambush laying, AK firing, and other assorted mayhem in Full Metal

They both have a similar humor and Main protagonist has the Exact same relationship with the female lead. Both are action filled with one of the leads being a gunslinger bad ass and the other being kind of hopeless.