The Underwater Tunnel is a fixed location to the south west of the starting zone added during the Update/03.07.2013 . It can be upgraded ten levels, all granting a higher increase to the Population Cap and gives access to the fourth^{[1]} expansion territory.

A total of 375

assets are needed to complete construction of the Underwater Tunnel. This is equivalent to 375

if one were to buy every asset instead of waiting to receive them from

neighbors .

Once the expansion is unlocked, the player is given the choice to build:

Quests and Achievements Edit
Quests

Requirements Edit

Underwater Tunnel (Level 1) Edit
Requires
Rewards
30 or 30 asset gifts
25 and 5
+10,000 to the Population Cap (Total: +15,000 )
750 when the last asset is placed

Underwater Tunnel (Level 2) Edit
Requires
Rewards
45 or 45 asset gifts
35 and 5
+25,000 to the Population Cap (Total: +40,000 )
1,000 when the last asset is placed

Underwater Tunnel (Level 3) Edit
Requires
Rewards
30 or 30 asset gifts
45 and 5
+15,000 to the Population Cap (Total: +55,000 )
750 when the last asset is placed

Underwater Tunnel (Level 4) Edit
Requires
Rewards
45 or 45 asset gifts
55 and 5
+25,000 to the Population Cap (Total: +80,000 )
1,000 when the last asset is placed.

Underwater Tunnel (Level 5) Edit
Requires
Rewards
30 or 30 asset gifts
65 and 5
+15,000 to the Population Cap (Total: +95,000 )
750 when the last asset placed

Underwater Tunnel (Level 6) Edit
Requires
Rewards
45 or 45 asset gifts
75 and 5
+25,000 to the population cap (Total: +120,000 )
1,000 when the last asset is placed

Underwater Tunnel (Level 7) Edit
Requires
Rewards
30 or 30 asset gifts
85 and 5
+15,000 to the Population Cap (Total: +135,000 )
750 when the last asset placed

Underwater Tunnel (Level 8) Edit
Requires
Rewards
45 or 45 asset gifts
95 and 5
+25,000 to the Population Cap (Total: +160,000 )
1,000 when the last asset placed

Underwater Tunnel (Level 9) Edit
Requires
Rewards
30 or 30 asset gifts
105 and 5
+15,000 to the Population Cap (Total: +175,000 )
750 when the last asset placed

Underwater Tunnel (Level 10) Edit
Requires
Rewards
45 or 45 asset gifts
115 and 5
+25,000 to the Population Cap (Total: +200,000 )
1,000 when the last asset is placed
Access to game zone expansion four
Ability to build the Prime Finance Center and following business centres

References Edit
↑ SQ forums, Player Help & Support, Post #1068