"Where are we ever going to use this?" is the question maritime students often ask. Not infrequently, even the mathematics professors themselves are not sure about the answer. A satisfactory answer requires an awareness of how mathematics is applied in maritime affairs. This book covers mathematical topics relevant to undergraduate studies at maritime higher education institutions. Lessons presented in a conceptual and often visual way are enriched with numerous applications, simulations and exercises and are suitable for use in the classroom and for individual learning. At the end of each chapter, there are real examples of the application of mathematics both in the maritime and other fields. This book aims to raise students' motivation for learning, involve them in the discussion and help them to generalise the material and apply it in new situations. All materials have been designed by the MareMathics project team for use by both mathematics teachers and students. MareMathics – Innovative Approach in Mathematical Education for Maritime Students, Grant No. 2019-1-HR01-KA203-061000, is an Erasmus+, KA2, Strategic Partnership project with the aim of supporting the creation and implementation of innovative practices in mathematics education for students of maritime studies across Europe, promoting cooperation of respective institutions, peer learning and exchange of experience among the teaching staff. Project Partners are University of Split, Faculty of Maritime Studies, Croatia; Tallinn University of Technology, Estonian Maritime Academy, Estonia; Latvian Maritime Academy, Latvia; Polish Naval Academy, Poland; Toni Milun – Independent Microenterprise, Croatia. We have developed a set of online interactive learning tools that accompany static lessons to help students study. In our lessons, interactivity is achieved using simulations - GeoGebra applets that allow students to change/control input parameters and observe results. Developed simulations with associated teaching packages can also be used for the preparation of lectures, activities in the classroom, and self-evaluation that students perform outside the classroom. Some of these simulations are included in this book. The authors believe that the material contained in the book is suitable for any student with the necessary mathematical skills. It provides enough foundation to bridge the different educational and mathematical backgrounds of most students. In addition, these materials can be used as an auxiliary tool in other courses at maritime higher education institutions, such as electrical engineering, physics, navigation, etc.