The Underwater Labs Add-on for Escape Dead Island has 10 achievements worth 245 gamerscore.
Complete the underground labs
Collect all of Ronald's logs
Acquire the assault rifle
Kill a Dweller using an environmental hazard
Stealth kill a Dweller
Find the underground labs
Acquire the walloper
Find all the underground secondary areas
Kill 10 enemies at long range with the walloper
Kill 100 enemies with the assault rifle