With the Book of Wisdom in his hands, Sam must now acquire the Holy Grail to ensure Mental's defeat.
- At the first village, on the left side at the start there is a house with a squeaking, moving door. Blast it to reveal a secret Serious Damage.
- At the windmill, there is a switch. Press it to summon a secret Santa, and shoot the Santa to get some bonus items (best done with either the Single Colt or the Flamethrower, to get as many items as possible).
- On the left side at the other half of the village, you may hear coughing noises. Keep moving to where you hear them louder, or simply check the chimneys of every house there is. You will find Santa's legs in one of these. Blast them to discover a "jammed Santa".
- In the same area, blast the Snowman with a rocket to reveal a secret armor.
- In the second village, at the start, pick up some armor to trigger a "snowman avenger" and quickly destroy him.
- The house on the right of the snowman avenger has a squeaking door. Blast it to reveal an invulnerability power-up.
- Opposite of #6, there is a another snowman with a switch on it. Press it to summon another secret Santa and repeat the procedure like secret #2.
- Before entering the lava caves, continously shoot rockets at the snowman to reveal an "incredible shrinking snowman", which in turn will spawn 2 Major Biomechanoids.
- In the first lava cave, you'll notice a gap in the stone bridge. Jump on it to be teleported to a secret Heart.
- As you enter the second lava cave, look for a glow in the distance up ahead. Zoom in with the Sniper Rifle to spot a platform with some cannonballs on it, then blast it with a Rocket. Proceed and collect it afterwards to register the secret.
- Before exiting the second cave, go behind the rocks on the left of the exit to discover a secret Cannon.
- In the third cave, when you are near the floating rock platforms, jump to the leftmost farthest one and wait until it transports you to some secret +200 armor.
- Before leaving the cave, go around the base of the arch bridge you crossed to discover a secret Heart.
- (HD-only)Before leaving to the Ice Castle, go to the right side of the cave, behind the second pillar is a teleport. Jump through it, and prepare to kill two Lava Golems as you do. After picking up the secret items there, jump in the middle of the four stone pillars, to a small rocky platform, to be teleported back.
- This level is named Winter Wonderland in Serious Sam Xbox.
- If you destroy the snowman avenger from secret #5, you will be granted Sniper ammo and thus the secret.