Optimal route planning for day tours in Marinduque, Philippines Destiny S. Lutero 1 • Gilbert Elvis A. Cerilo 1 • Allyssa M. Eustaquio 1 • Christian Alvin H. Buhat 2 • Aldrin O. Nazareno 3 • Allen L. Nazareno 1 • Arnold R. Salvacion 4 Received: 30 May 2021 / Revised: 23 November 2021 / Accepted: 26 November 2021 Ó Korean Spatial Information Society 2021 Abstract Island day tours have become a ubiquitous inclusion in travel itineraries. Marinduque is one of the Philippine islands where its major tourist attractions can be covered by day tours. This study determines an itinerary of select tourist spots for island day tours in Marinduque. The longitude, latitude of each tourist spot and the pairwise road distances were determined. Every tour was assumed to start and end at the same point, either at Marinduque Airport or at Balanacan Port, and would last for at most 8 h. To determine the optimal route for the different types of tours (general and themed), an integer programming model was formulated. Balanacan port is the point of origin for three of the four identified tours. The general tour is the ideal choice for those who want to maximize theme diversity. The history-themed and church-themed tours are covered in at least three of the four tours. All tours ran from 7.5 to 8 h. All themed-tours covered their themed points except for the cave-themed. All points except one were visited in at least one tour. Three of the four pilgrim points were visited in all tours, while the cave sites were only visited in the cave-themed tour. The results of this study are beneficial to the community of Marinduque, as these will contribute to the tourism management plan of the province. The model may be extended to consider other tourist destinations. Keywords Travel itinerary  Traveling salesman problem  Tourism  Tour time  Integer programming model 1 Introduction Tourism has been an important driver of economic growth for various countries over the recent years. There has been a rapid growth in the tourism industry due to the increase in the interest of people to travel for recreation and leisure. With the progression of tourism comes the need of inno- vation in improving travel experience [1]. Nowadays, many tourists rely on themselves to manually prepare tour itineraries, which are tedious to make [1, 2]. A tourism management plan that includes recommended tour itiner- aries would be beneficial to travelers as it allows them to efficiently access popular tourist attractions [3]. This would also boost the local tourism, creating livelihood opportu- nities for the people in the community [3]. Multiple sources (e.g., magazines and travel websites) offer itineraries for tourists, but the optimality of these in terms of the number of visited tourist spots and time allotment in each spot are yet to be determined [1, 4]. Personal preferences, nature of travel, and time availability are some of the important considerations for a tour itinerary which makes optimiza- tion of tour routes useful [1, 5]. Route optimization is part of a more general spectrum of problems under spatial optimization where different approaches are used to solve the problems [6]. In spatial optimization, integer programming (IP) and heuristics are & Destiny S. Lutero dslutero@up.edu.ph 1 College of Arts and Sciences, Institute of Mathematical Sciences and Physics, University of the Philippines Los Ban ˜os, Victoria M. Ela St., Los Ban ˜os 4031, Laguna, Philippines 2 University of Houston, Houston, TX 77204, USA 3 Buenavista National High School Bagacay Annex, Bagacay, Buenavista 4904, Marinduque, Philippines 4 Department of Community and Environmental Resource Planning, College of Human Ecology, University of the Philippines Los Ban ˜os, Harold Cuzner Royal Palm Avenue, Los Ban ˜os 4031, Laguna, Philippines 123 Spat. Inf. Res. https://doi.org/10.1007/s41324-021-00424-3