Preheat oven to 350°F. Grease and flour a 9x5-inch loaf pan.
In a medium bowl, whisk together flour, baking soda, salt, cinnamon, nutmeg, and ginger.
In a large bowl, beat together 1½ cups sugar, oil, and 2 eggs until well combined.
Stir in pumpkin puree and water until smooth.
Gradually add dry ingredients to wet ingredients, stirring just until combined. Don't overmix!
In a separate bowl, beat cream cheese, ¼ cup sugar, egg yolk, and vanilla until smooth and creamy.
Pour half the pumpkin batter into the prepared pan. Spoon cream cheese mixture over the batter, then top with remaining pumpkin batter.
Use a butter knife to gently swirl the cream cheese through the batter, creating a marbled effect.
Bake for 60-70 minutes, or until a toothpick inserted in the center comes out clean.
Cool in pan for 10 minutes, then turn out onto a wire rack to cool completely before slicing.