Is Southern Island reachable in normal play in Ruby and Sapphire?

Not without the Eon Ticket. Southern Island opens only with that promotional item, handed out years ago, after which a ferry option appears. On the island you battle a level 50 Latias in Ruby or Latios in Sapphire, the opposite of your roaming Eon.

Ruby & Sapphire Southern Island

Only the event-only Eon Ticket opens this hidden islet. In its lone clearing waits the eon twin that doesn't roam. That's Latias in Ruby and Latios in Sapphire, with a single chance to catch it.

Southern Island is in Hoenn. In the story it comes after Roaming Hoenn.

SOUTHERN ISLAND MAP

Ruby & Sapphire

Southern Island Walkthrough

0 trainers 1 item 0 species

Only a holder of a special event ticket can reach Southern Island, and only after the main story.

The harbor ferry heals your team and sails you there, and you walk north from the dock into the trees.

1From the forest entrance, go north through the shallow pond to the stone tablet.
Legendary encounter (Ruby only)
LatiasLv 50
On Southern Island — requires the Eon Ticket event item and the S.S. Tidal after entering the Hall of Fame; holds a Soul Dew
In Ruby, read the tablet to battle Latias as it swoops down to you, and you get only one try
Legendary encounter (Sapphire only)
LatiosLv 50
On Southern Island — requires the Eon Ticket event item and the S.S. Tidal after entering the Hall of Fame; holds a Soul Dew
In Sapphire, the same tablet lets you battle Latios instead
Soul Dew
Whichever one you battle, catch it to take the Soul Dew it holds

Pokemon Encounters

The Eon Ticket islet holds the twin that does not roam: Latias in Ruby, Latios in Sapphire, a stationary level 50 catch. It was an event-only island, so most players meet their Lati through the roamer instead.

✦Special encounters2

#380Latias

Legendary Lv 50

Ruby

#381Latios

Legendary Lv 50

Sapphire

Legendary

#380

Latias

DragonPsychic

Level

EV yield

3 Sp. Def

Acquisition

Legendary

Requires Eon Ticket event item

at Forest

Sealed locationForestSouthern IslandView on map

One-of-a-kind. You only get a single shot per cartridge — knock it out or run, and it is gone for the run. Save before engaging.

Latias page →

ITEMS

Southern Island holds the Soul Dew, the held item that sharply boosts the Special stats of Latias or Latios, making the Eon Ticket trip worth the effort on its own.

Item ball2

Soul Dew

ITEM BALLRuby

Soul Dew

Held by Latias

Effect

Hold item: Raises SP. ATK & SP. DEF of LATIOS & LATIAS.

Item ball2

Soul Dew

ITEM BALLRuby

Soul Dew

Held by Latias

Effect

Hold item: Raises SP. ATK & SP. DEF of LATIOS & LATIAS.

Soul Dew

ITEM BALLSapphire

Soul Dew

Held by Latios

Effect

Hold item: Raises SP. ATK & SP. DEF of LATIOS & LATIAS.

Southern Island Guide

Not without the Eon Ticket. Southern Island opens only with that promotional item, handed out years ago, after which a ferry option appears. On the island you battle a level 50 Latias in Ruby or Latios in Sapphire, the opposite of your roaming Eon.