A Marine throws an M67 Grenade into a trench during Operation Lava Viper, a company assault exercise at Pohakuloa Training Area, Hawaii, June 9, 2015. A Marine throws an M67 Grenade into a trench during Operation Lava Viper, a company assault exercise at Pohakuloa Training Area, Hawaii, June 9, 2015. SHARE IMAGE: Download Image: Full Size (2.2 MB) Tags: Photo Essays Photo By: VIRIN: 949676-Q-XKT33-168.jpg Photo Gallery