Two ability scores of your choice each increase by 1.

Lung dragonborn have about double the lifespan of their non-dragon parent(s). For example, a lung dragonborn whose father was a Chiang Lung and mother was a human or whose parents were both humans with an ancestor blessed by a lung would have a lifespan of about 200 years.

With the exception of Tun Mi Lung, the lung typically have a lawful and good alignment. While lung dragonborn can be heavily influenced by the nature of their draconic ancestor they can still be of any walk of life with their own ideals and alignment. 

Lung dragonborn are the same size as their non-dragon parent(s), with slightly larger builds. Your size is Small or Medium.

Your base walking speed is 30 feet.

You have draconic ancestry. Choose one type of dragon from the Draconic Ancestry table. Your breath weapon is determined by the dragon type, as shown in the table. Not all lung have breath weapons, if there is 'Other' on the table you instead gain spellcasting based on your draconic ancestor. 

In addition, lung dragonborn are at home in any body of water or mountain range. You are immune to the effects of cold weather and frigid water as described in page 110 of the DMG. You also gain a swimming speed of 30 feet and can breathe underwater.

Draconic Ancestry

Chiang Lung
You conjure a wave of water that crashes down on enemies in a line 30 foot long 5 feet wide originating from you. The target must succeed a Strength saving throw, taking bludgeoning damage equal to your draconic ancestry damage on a failed save, or half as much on a successful save. The water then spreads out and extinguishes unprotected flames in its area and within 10 feet of it.
Li Lung
You have inherited some of the Li Lung's power over the earth. You know the mold earth spell. At 3rd level, you can cast the earth tremor spell once using this trait. At 5th level, you can cast the maximilian's earthen grasp spell once using this trait. You must finish a long rest before you can cast either spell this way again. You can also cast these spells using any spell slots you have. Your spellcasting ability for these spells is Constitution. You also do not require material components for casting these spells. 
Lung Wang
You let out a burst of hot steam in a 15 foot cone originating from you. Creatures within range must succeed on a Dexterity saving throw, taking fire damage equal to your draconic ancestry damage on a failed save, or half as much on a successful save. Being underwater doesn't grant resistance against this damage.
Pan Lung
You have inherited some of the Pan Lung's mastery over illusions. You know the minor illusion spell. At 3rd level, you can cast the silent image spell once using this trait. At 5th level, you can cast the mirror image spell once using this trait. You must finish a long rest before you can cast either spell this way again. You can also cast these spells using any spell slots you have. Your spellcasting ability for these spells is Constitution. You also do not require material components for casting these spells. 
Shen Lung
You have inherited some of the Shen Lung's power over nature. You know the guidance spell. At 3rd level, you can cast the speak with animals spell once using this trait. At 5th level, you can cast the spiritual weapon spell once using this trait. You must finish a long rest before you can cast either spell this way again. You can also cast these spells using any spell slots you have. Your spellcasting ability for these spells is Constitution. You also do not require material components for casting these spells. 
T'ien Lung
You exhale fire in a 15 foot cone originating from you. Creatures within range must succeed on a Dexterity saving throw, taking fire damage equal to your draconic ancestry damage on a failed save, or half as much on a successful save.
Tun Mi Lung
You have inherited some of the destructive power of Tun Mi Lung. You know the thunderclap spell. At 3rd level, you can cast the thunderwave spell once using this trait. At 5th level, you can cast the darkness spell once using this trait. You must finish a long rest before you can cast either spell this way again. You can also cast these spells using any spell slots you have. Your spellcasting ability for these spells is Constitution. You also do not require material components for casting these spells. 

When you take the Attack action, you can replace one of your attacks with a burst of destructive energy. Your draconic ancestry determines the size, shape, and damage type of the breath weapon. When you use your breath weapon, each creature affected must make a saving throw, the type of which is determined by your draconic ancestry. The DC for this saving throw equals 8 + your Constitution modifier + your proficiency bonus. A creature takes 2d8 damage on a failed save, and half as much damage on a successful one.

The damage increases to 3d8 at 5th level, 4d8 at 11th level, and 5d8 at 17th level. You can use this trait a number of times equal to your proficiency bonus, and you regain all expended uses when you finish a long rest.

Alternatively, you have access to spellcasting based on your draconic ancestry. 

You can speak, read, and write Common, Celestial, and Draconic. Draconic is thought to be one of the oldest languages and is often used in the study of magic. The language sounds harsh to most other creatures and includes numerous hard consonants and sibilants. Celestial is the language commonly spoken by Lung and other members of the Celestial Bureaucracy, often through its subtypes of celestial court or spirit tongue. 

Thanks to your draconic ancestry, you have superior vision in dark and dim conditions. You can see in dim light within 60 feet of you as if it were bright light, and in darkness as if it were dim light. You can’t discern color in darkness, only shades of gray.

As part of your draconic heritage parts of your skin are covered by a thin sheen of dragon-like scales (if your ancestor is a Li Lung you are instead covered in coarse black fur. You determine how much there is). When you aren't wearing armor, your AC equals 13 + your Dexterity modifier. You can use your natural armor to determine your AC if the armor you wear would leave you with a lower AC. A shield's benefits apply as normal while you use your natural armor.

Chiang Lung

Also known as river dragons, Chiang Lung reside in small bodies of water. Covered with scales of green or blue shades and a yellow underside, often polymorphing into humans. They serve the Celestial Bureaucracy as guardians of rivers and lakes, controlling the rain of nearby land and ruling over the water denizens in their jurisdiction. They rarely show themselves to humanoids and dwelt at the bottom of rivers or lakes in palaces. 

Li Lung

Also known as earth dragons, Li Lung reside deep underneath Kara-Tur. Li Lung shed their scales at a young age and instead grow coarse black fur across their bodies. They possess the mane of a lion and peacock feathers on their tails and are the only Lung to possess physical wings. Within the Celestial Bureaucracy the Li Lung control the earth, living in labyrinthine caverns deep underground.  

Lung Wang

Also known as sea dragons, Lung Wang resides in the oceans surrounding Kara-Tur. Distant cousins of dragon turtles, Lung Wang resemble giant draconic turtles covered in a shell of thick green scales speckled with silver scales and flippers as arms. Lung Wang serve the Celestial Bureaucracy as the guardians of sea creatures. They are very territorial but remain friendly with most other Lung and sea creatures, using their powerful steam breath whenever combat arises.  

Pan Lung

Also known as coiled dragons, Pan Lung dwell in the crypts and temples of Kara-Tur. They can have any shade of colored scales, though green, orange, and red scales are the most common, with their scales being naturally oily. Within the Celestial Bureaucracy Pan Lung serve as the guardians of hidden places, with their servants often being humans punished by the Bureaucracy for not being loyal to their families. 

Shen Lung

Also known as spirit dragons, Shen Lung dwell in rivers and lakes. They are born with dull gray scales that are eventually replaced with bright shades of green, orange, or red. They are more modest than most other true dragons and maintain cordial relationships with nature spirits. Within the Celestial Bureaucracy Shen Lung work as assistants to Chiang Lung and possess the ability to communicate with animals.  

T'ien Lung

Also known as celestial dragons, T'ien Lung are often found residing in the mountains of Kara-Tur. Their long serpentine bodies  are covered with dull gold scales that turn into a bright yellow hue as they grow older, though some are covered in light green or orange scales. They possess multicolored beards and long whiskers that rise over their heads. While arrogant they are also noble and honorable and possess the ability to breathe a cone of fire. Within the Celestial Bureaucracy T'ien Lung are in control of all weather except for rain and are often guarded by air elementals in palaces found in clouds and on the peaks of mountains. 

Tun Mi Lung

Also known as typhoon dragons, Tun Mi Lung live in the oceans of Kara-Tur. Covered in thick scales of blue-green, dark red and violet they are the largest of the Lung. They are aggressive and malicious, disliked by most other creatures and they did not respect the territory of other dragons. They spend most of their flying across the coast and ocean waters, dwelling in underwater palaces on the ocean floor. Within the Celestial Bureaucracy Tun Mi Lung were tasked with unleashing ocean storms, typhoons and hurricanes when ordered by the Celestial Bureaucracy but often did so on their own whim, requiring a T'ien Lung to be sent to end the storm and chastise the Tun Mi Lung.