When a Mech's armor is damaged cracks and holes can be formed. This is what can result in flooded locations in underwater combat.
Examples of this occur in Warrior Coupe:
Andrew blasted an Enforcer that barred his way to the Palace 'Mech bay. The Liao 'Mech's autocannon blew a series of craters into the armor over the Marauder's right thigh while the large laser burned a scar across the heavy 'Mech's left arm. Andrew's assault, mixing the PPC and medium laser of his right arm with the torso-mounted autocannon's metal storm, stripped the armor off the Enforcer's right side.
Like a living creature suffering a stroke, the Enforcer shuddered when its right flank ignited. The torso muscles controlling movement of the right arm burned through in an instant, dropping the autocannon's muzzle toward the ground. At the same time, thigh muscle insertions in the abdomen melted away. Robbed of stability and mobility, the Enforcer crashed to the ground.
...
Swirling through the green mist, a Liao Crusader charged at Andrew. In an instant he dropped the Marauder's targeting crosshairs on the humanoid 'Mech's outline, then triggered both PPCs. Dancing forks of blue lightning rippled up and down the Crusader's right arm. Glowing gobs of molten armor dripped from the 'Mech like liquid glass. Exposed by the PPC assault, myomer muscles, blacker and heavier than those familiar to Andrew, contracted to bring the arm-mounted laser into play.
Suddenly, the muscles began to smolder. An oily vapor rose from them as the Crusader's pilot struggled to make the limb respond, then the muscles burst into flame. Burning droplets of molten myomer splashed over the Crusader's leg and streamed to the ferrocrete. The limb, engulfed in the fire of its own muscles, swung like a man hanging from a gibbet.
Andrew opened a radio frequency to Morgan. "It works. Exposed to the gas, the myomer they stole from Bethel ignites when they run power through it to make it contract!"
