Current collaboration applications such as Zoom, Skype, and Microsoft Teams still fail to meet the immersive telepresence challenge of - “sense of presence”. Low-resolution single viewpoint video stream, limited interaction with remote location, and limited spatial context, contributing to lack of spatial perception as well as lack of social and visual cues. With the advent of multi-user display and tracking technology, immersive projection hardware, and pre-built 3D scene settings, group immersion is now supported for co-located users. But these solutions are often cumbersome, lack detail in dynamic environments, and lack multi-user capabilities. Much of the past research has focused on one-to-one collaboration, and multi-user immersive collaboration is still a relatively new area of re- search and requires many problems to be addressed before it can be used on a large scale. This thesis will explore this multi-user aspect of immersive collaboration, where n-number of co-located and remotely located users can immerse into a single or merged collaboration space. An immersive platform will be developed to allow multiple users in different locations across multiple devices to collaborate and communicate together. From there, to al- low users to explore data visualization in a multi-user extended reality collaboration environment, a collaborative immersive analytics application will be developed in which users can utilize the space around them and at the same time can collaborate and switch between perspectives of other co-located users. The system will be evaluated for technical performance and user experience. The evaluation will examine how users perceive and interact with remote and co-located users to complete a collaborative task, levels of presence, spatial awareness, and whether flexible viewpoint management enhances collaborative and immersive data visualization scenarios.