You can already pass big arrays to unmanaged code without copying just fine: allocate a GCHandle of type Pinned, and pass AddrOfPinnedObject as the pointer. Th

You can already pass big arrays to unmanaged code without copying just fine: allocate a GCHandle of type Pinned, and pass AddrOfPinnedObject as the pointer. The use case for Span is more within the managed realm: it allows pointer-like manipulation of memory, without having to special-case it for each type. And although anything with pointers is of course asking for trouble to some extent, you don't lose any safety in most scenarios (those not involving obvious giveaways like 'unsafe'...)