In this scene, our male character steps his kneehigh leather platform boots into deep mud. Slowly, he sinks deeper until his boots go under the quicksand and he is up to his knees. He wasn't quite expecting to sink even deeper up to his thighs! His jeans and boots are quickly ruined as the mud takes him deeper and he becomes more stuck.
Soon, our protagonist is able to escape from the thicky grasp of the thick ooze and steps his ruined boots onto the bank, dripping with squelchy mud.