A group of students assembled a puzzle of pieces of islands to form a map of Indonesia. They worked hard to arrange the puzzle according to the correct composition. But in reality, not every group can arrange it properly. These 'games' started the activities of Stube HEMAT Yogyakarta and students to explore holistically the Marine Economy, where students studied Indonesia as an archipelagic country, discovered Indonesia's marine potencies and breakthroughs in cross-sectoral collaboration for the marine economy, and students played role in promoting and making Indonesian people aware of sea potencies. Indonesia consists of land and sea with 17.508 islands, which bring a term of 'archipelagic state' based on the 'United Nations Convention on the Law of the Sea' (UNCLOS) December 10, 1982, in Montego Bay, Jamaica. (21/1/2023).

The first activity in the Marine Economy program is a book review on 'Maritime Security and the Blue Economy: Sustainable Marine Economic Transformation in Indonesia' by Humphrey Wangke, published by the Pustaka Obor Indonesia Foundation, 2021. Trustha Rembaka presented material on a sustainable marine economic model to improve the economy of coastal communities and food security, making the sea a global energy source, and becoming a safe area for international trade traffic, such as the goals of the Blue Economy. The Blue Economy will drive economic growth, and improve lives and social inclusion without compromising the sustainability of the marine environment and coastal areas because marine resources are limited and their physical condition has been harmed by human actions.

Furthermore, Daniel Prasdika explained Maritime Security and the Urgency of Bakamla's Presence in Securing Indonesian Waters. Indonesia's territory consists of land and sea areas, two-thirds of Indonesia's territory is the sea. Its existence has great marine wealth potency which provide options for development, however, the wider the ocean the harder the consequences of managing the ocean area and everything in it for the people’s welfare and maintaining its sustainability. Indonesian waters are vulnerable to maritime crimes, such as the smuggling of fuel oil, and drugs, violations of the maritime territory, human trafficking, and smuggling of dangerous substances, so maritime security agency (Bakamla) is needed to oversee and maintain its security.

Furthermore, Daniel conveyed sustainable marine management based on improving the economy of the marine sector with the four pillars of sustainable marine development, including sustainability, inter-generational equality, intra-generational equality, and public participation. The four pillars of development are guides for the better management of marine resources.

The discussion on 'Challenges to Sustainable Marine Economic Management' was presented by Kresensia Efrieno, who discussed plastic waste in the sea which increase criticaly because the world's production of plastic waste is increasing from year to year. It was recorded that the world's production of plastic waste in 2008 reached 260 tons, in 2013 reached 299 tons, and in 2016 increased by 77% to 1.3 billion tons, and 8 million tons of it was wasted away into the sea. It is even predicted that in 2025 there will be more plastic waste than fish! It harms marine ecosystems and their sustainability. World organizations and the United Nations carry out several campaign programs to reduce plastic waste at the sea.

This book review enriched students' insights to 'voyage' to Indonesian seas and opened their minds to find creatively some  marine-based entrepreneurial ideas so that they have economic value to increase welfare. ***