Walking along trails in natural areas is a rewarding experience, but visitors sometimes need proper assistance to enhance their enjoyment, maximize learning, and ensure safety. Over the years, various signage techniques have been introduced, but today, the widespread use of smartphones offers new opportunities for visitor support. In this paper, we outline the key principles for designing an Android app tailored for geotourists. Our approach begins by defining user personas and deriving app requirements based on their needs. We then present a proof of concept that addresses the critical aspects identified during the design process.