• Proposed undersea tunnels by continent (6 C)

A

• Undersea tunnels in Africa (1 C)
• Undersea tunnels in Asia (1 C, 19 P)

E

• Undersea tunnels in Europe (3 C, 16 P)

N

• Undersea tunnels in North America (1 C, 3 P)

O

• Undersea tunnels in Oceania (1 C, 2 P)

S

• Undersea tunnels in South America (1 C)