In the 1970's existed Innerspace Systems, a division of Innerspace Services Corp, now defunct. In 1999 we bought the remains of Innerspace Systems and formed InnerSpace Systems Corporation, dedicating our existence to the research, development, and manufacture of rebreather diving systems, first focusing on fully closed circuit systems. Our first efforts were to concentrate on the technical sport and commercial diving arena. In 2006, we now have 3 variations of our Megalodon variable volume mixed gas closed circuit rebreather system in the field with more varieties and exciting improvements in the horizon. This page provides a brief comparison between the 1970s era Porpoise Pack I and the modern Megalodon, both having the same depth capabilities.