I was going to ask what this setting does, but found the documentation on the wayback machine:
Added "Allow Mermaid Routing"
- Disables the obsession with mermaids to swim everywhere.
I'm playing a mermaid in Isla Paradiso and he swims everywhere regardless of what I have this set too. He's got the AquaSled in inventory and set as his preferred boat, but doesn't use it unless I direct him to 'boat here.' Is this setting supposed to be working or am I not doing it right?