This paper underscores the importance of environmental monitoring, and specifically of freshwater ecosystems, which play a critical role in sustaining life and global economy. Despite their importance, insufficient data availability prevents a comprehensive understanding of these ecosystems, thereby impeding informed decision-making concerning their preservation. Aerial-aquatic robots are identified as effective tools for freshwater sensing, offering rapid deployment and avoiding the need of using ships and manned teams. To advance the field of aerial aquatic robots, this paper conducts a comprehensive review of air-water transitions focusing on the water entry strategy of existing prototypes. This analysis also highlights the safety risks associated with each transition and proposes a set of design requirements relating to robots' tasks, mission objectives, and safety measures. To further explore the proposed design requirements, we present a novel robot with VTOL capability, enabling seamless air water transitions.