Spleen projects into the following space of peritoneal cavity:

Being developed in the dorsal mesogastrium, the spleen projects into the greater sac surrounded by peritoneum of the original left leaf of the dorsal mesogastrium. It lies at the left margin of the lesser sac below the diaphragm, and its diaphragmatic surface is moulded into a reciprocal convexity. Its hilum lies in the angle between the stomach and left kidney, each of which impresses a concavity alongside the attached the splenic vessels. Ref: Last's Anatomy: Regional and Applied By Chummy S. Sinnatamby, 2011, Chapter 5.