Step 1: First blank.
Dragging feet in the Himalayas = walking through partially melted snow/ice. The correct word is
slush.
Step 2: Second blank.
The Ganges delta = muddy, viscous mixture of water and solids. The correct word is
sludge.
Step 3: Third blank.
Children in the sea = playful movement with splashing sound. The correct word is
sloshing.
Step 4: Verify sentence.
Final version:
\[
\text{...drag my feet through the slush... negotiating the thick sludge... my children sloshing about in the waters...}
\]
This is both contextually and grammatically accurate.
\[
\boxed{\text{slush, sludge, sloshing}}
\]