Gap in seam

[benjaminp]

Hi there, I'm new to 3D printing and have just begun playing with the software. I am using Cura to slice something I have created and I am trying to get the seam as straight and small as possible. In the preview it looks like the seam is actually a hole straight through to the inside of the piece. Is this accurate? Is there a setting to control the width of the seam to close it up? I've attached a reference photo of what I am seeing in Cura. Thanks