Photoautotrophic microorganisms have garnered notable focus in the last few years for their potential in the sustainable production of biofuels, dietary supplements, cosmetics, and biofertilizers. Algae, in particular, show promise in addressing global energy crises, food demand, and rising environmental CO2 levels. However, the economic viability of algae cultivation remains in question due to its high cultivation costs, which account for more than 50% of total production expenses. Cultivating algae in open photobioreactors is an economical method due to its low operational costs and ease of monitoring. Nevertheless, this approach faces several challenges, including low productivity, a higher risk of biological contamination, dependency on weather conditions, evaporation losses, inefficient CO2 utilization, significant space and land requirements, and nutrient management issues. The present chapter discusses different types of photobioreactors used in open algal cultivation, along with their advantages, challenges, and large-scale studies demonstrating their commercial scalability. Additionally, it extensively examines the various factors that affect algae cultivation in open systems and provides detailed strategies for addressing these challenges in an economically viable manner. Furthermore, the chapter covers prospects for algae cultivation in open systems, such as the use of artificial intelligence to design optimal open photobioreactors and the development of hybrid photobioreactors. This chapter offers a forward-looking analysis of open photobioreactors, addressing challenges, exploring innovations, and highlighting their potential for advancing sustainable algae cultivation.