Antonyms for the word "backwaters" are "mainstream," "thriving," "central," and "developed." These words describe areas that are highly populated and well-developed, with thriving economies and bustling city centers. Unlike backwaters, these areas are considered to be the hubs of commerce, culture, and innovation. They are known for their modern amenities, sophisticated infrastructure, and higher quality of life. In contrast, backwaters are often rural, isolated, and stagnant places, with limited opportunities for growth and development. Therefore, antonyms for backwaters represent the opposite end of the spectrum, reflecting the vibrancy and vitality of prosperous urban centers.