You wouldn't go out running without wearing socks under your sneakers. Similarly, you shouldn't go diving without dive socks!
Dive socks are a must for all spearfishers and serve a range of purposes such as preventing blisters, keeping your feet warm and ensuring that you get a perfect fit from your spearfishing fins.
Dive socks are generally 2 or 3 mm and shouldn't take up much room in your foot pocket, so your size shouldn't change - just like it wouldn't if you were wearing socks with a pair of shoes!
The Scuba Doctor also stocks a range of dive boots. Dive booties will not fit as well under typical closed heel, freediving fins but are useful because of the grip and protection that they provide when you are on a boat or walking on rocks and reef.