<p>Underwater Acoustic Networks (UANs) are critical for enabling long-range underwater communication, supporting a wide range of applications, such as environmental monitoring, resource exploration, disaster prevention and marine security. Unfortunately, UANs operate within a limited acoustic spectrum, where these spectrums often overlap with those used by marine animals for communication, navigation and foraging. Additionally, anthropogenic noise from industrial activities contributes to acoustic pollution, intensifying this problem. This frequency overlap poses significant risks to marine life. Therefore, this review highlights the urgent need to develop environmentally aware UANs that minimize harmful acoustic interference with marine mammals, fish and invertebrates. Further, it focuses on network design challenges, examining their negative impacts, defining the concept of a marine-friendly network and establishing evaluation metrics to assess performance. This paper classifies existing marine-friendly UAN approaches into three main categories: spectrum management methods (including cognitive acoustic technologies), eco-friendly routing protocols, and prediction-based techniques. Each category is analyzed in terms of its strengths and limitations. Lastly, the review identifies current research gaps and outlines future directions to support the development of marine-friendly UANs that can effectively balance communication performance with marine conservation, toward a sustainable network.</p>