Swimming

The ability for GTA protagonists to swim in deep bodies of water was introduced in Grand Theft Auto: San Andreas, and has since been seen in Grand Theft Auto: Vice City Stories, Grand Theft Auto IV, and Grand Theft Auto: Chinatown Wars.

Pre-GTA San Andreas
Prior to GTA San Andreas, bodies of water were lethal obstacles that acted as boundaries to prevent players from reaching locked areas. In Grand Theft Auto 1 and Grand Theft Auto 2, the player is instantaneously wasted when they fall into water, regardless of whether or not they are in a vehicle. In Grand Theft Auto III and Grand Theft Auto: Vice City, falling into deep water is immediately lethal, and the protagonist will rapidly lose health if they wade more than chest-deep into the water.

GTA San Andreas debuted swimming as an ability. However, Grand Theft Auto Advance and Grand Theft Auto: Liberty City Stories do not allow swimming (with exposure to water in LCS being once again near-instantly lethal). Liberty City Stories is the last game of the series thus far to disallow swimming.

GTA San Andreas
In GTA San Andreas, the player can float (in a water treading position), and swim in any deep body of water using directional controls. The player can perform a breaststroke to swim at a slow pace; holding the sprinting key or button allows the player to perform a faster front crawl. Tapping the sprint key or button rapidly adds slightly more speed.

The player can dive underwater by using the "fire" key or button while in water. This allows the player to swim deep underwater using directional controls; the sprint key or button gives the player forward movement.

Whenever the player enters water, a white bar denoting the player's oxygen appears on the game's HUD, beneath the Health and Armor bars. When underwater or in a sinking vehicle, the bar will gradually empty; when exhausted, the player's health will be reduced instead, leading to eventual drowning. The oxygen bar is replenished by returning to the surface of the water. The player's lung capacity determines how long the player can stay underwater, and is improved both by continuously diving and by collecting Oysters. The player can tread water and swim on the surface of the water indefinitely.

Diving allows the player to sneak past guards undetected in some missions, and can be used to explore the waters of San Andreas, revealing other secrets. In addition, the ability to swim allows the player to enter locked regions before they officially open, leading to a major wanted level in the process.

To date, like most features of a GTA game, San Andreas still possesses the most sophisticated swimming system in the series.

GTA Vice City Stories -- GTA Chinatown Wars
Following GTA San Andreas, three games have employed a swimming feature, but all employ simplified versions of GTA San Andreas' game mechanics, with the diving element absent.

While GTA Vice City Stories allows the player to swim, it only permits swimming for a limited amount of time, determined by a "stamina" bar which decreases as the player remains in the water. When the bar runs out, the player's health decreases, followed by drowning. This is to prevent the player from swimming across to still-locked areas. The player, however, can give the main character infinite stamina by beating the "Beach Patrol" side mission (by which time all regions of Vice City have been unlocked anyway).

In GTA IV and GTA Chinatown Wars, the player may stay in the water for as long as they please; during multiplayer sessions in GTA IV, however, the player will begin to lose health after a certain amount of time in the water. Also in GTA IV, the player cannot swim underwater.

Missions involving swimming
GTA San Andreas
 * Amphibious Assault
 * The Da Nang Thang
 * Vertical Bird
 * Beat the Cock! (2 optional side missions)

GTA Vice City Stories
 * Soldier

GTA IV
 * Waste Not Want Knots
 * A Revenger's Tragedy

GTA Chintown Wars
 * Yu Jian