Serious Sam 3, BFE, Secrets: 11 The Last Man on Earth

Secret. Ammo (minigun bullets +100). Inside the temple you get to a steep shaft with a large boulder at the top of it (think Indiana Jones). At the top of this shaft (to the left of where the boulder was) you find a small niche with the ammo inside it

Mini secret. Armor (+10). Just outside the temple/underground complex you see a container with some ammo inside it. Behind it you find the helmet.

Secret. Laser. Just before heading into the museum, you'll see a sort of stone tower. It's hollow, so crawl up top and inside to pick up the laser.

Secret. Sniper rifle. On the other side of the museum, just before heading into the village, there's a building at the end with some pillars (unless you blew them up). The back wall has a small alcove/niche. Look up and see a box blocking a hole in the roof. Shoot it to get the rifle.

Secret. C4 (+7). Just inside the village, turn left and head through the exit in the wall. Follow the road/path outside past the first dune to find the secret to the left of the path.
Secret. Armor (+25). Opposite side of secret #5. To the left of the exit (outside the wall), you'll find the armor.
Secret. Ammo (Sniper bullets +3). The red two-story house by secret #5, has a balcony. On the edge of it you'll find the ammo. Get to it by climbing onto the white wall at one of the ends.
Mini secret. Health (+25). In the corner of the white wall by secret #7.
Secret. Ammo (Electricity +150). The tallest building on the map (right hand side, further away from the museum than secrets 7 and 8) has a small yard completely fenced in. Jump over it using the boxes to pick up the ammo.
Secret. Ammo (Electricity +150). By the car you leave with, turn around and face the museum. To the right is a small T-shaped building with some shells and armor on boxes next to it. Jump onto the roof using the boxes to pick up the ammo.
Secret. Ammo (Minigun bullets +100). By the end of the map, top left corner (back to the museum), there's a small grouping of palms (four) and a collapsed wall. Behind the wall you find the ammo.