Final answer:
The novel contrasts the depictions of the fresh-water river and the sea to establish a tone that explores the relationship between society and nature. Twain's descriptions show both the natural beauty of the river and the negative effects of societal presence, challenging the idealization of nature. The sea is portrayed in a way that underscores its vastness and the human life it influences.
Step-by-step explanation:
The contrasting depictions of the fresh-water river and the sea at the beginning of the novel create a nuanced tone that reflects the complexity of the relationship between society and nature. On the one hand, the river scenes painted by Mark Twain in Huckleberry Finn are imbued with a sense of natural beauty and tranquility, as detailed in the vivid descriptions of the sunrise and the life on the raft, suggesting an idealized view of nature. On the other hand, the presence of society along the river is marked by pollution and negative connotations which seem to corrupt this natural beauty, as seen in the description of the smoky town and the 'piled by cheats' woodyard.
However, this initial perception is challenged when the narrative presents how the absence of human activity on the river leads to a feeling of 'solid lonesomeness', hinting at the complexity of human interaction with the environment and the subtle interdependence between the two. Meanwhile, the sea is depicted through reflections on its vastness and the life it encompasses, ranging from the stories of Mrs. Ebbling's life swept along by the ocean currents to the stark image of two lights being the only 'furniture of the world' on the open sea at night.
Thus, these descriptions contribute to the tone of the novel by capturing the duality of nature as both a space of freedom and beauty, and as a space that cannot be entirely separated from the societal constructs that exist alongside it. It provokes reflection on the relationship between human beings and the natural world, as well as the persistent impact of human endeavors on environments that are often romantically idealized.