Bears are found on Balboa Island as well as smaller islands around Balboa, but stick to Balboa as the bears respawn here, like the lurkers do on the Vasagatan.
Bears hit decently hard and have 3 different attacks. They have a leap (similar to the lurkers), they have a swipe (also like lurkers), and they have a stomp. With all of these attacks you want to be moving in and out of the bear's range as they will be mostly stationary while doing attacks (aside from the leap if you get too far away). Get in one or two spear stabs between the bear's attacks because if you are circle strafing around and get caught in an attack, it can be bad news. You can use a bow but it can be difficult to find a safe place to stand that the bears can't reach and it also takes quite a few arrows per bear. Better to save all of your arrows for when it comes time to fight the Mama Bear. Bears will take 10 stabs from a metal spear to kill.