race features:
Darkvision. Accustomed to life underground, 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 colour in darkness, only shades of grey.
Dwarven Resilience. You have advantage on saving throws against poison, and you have resistance against poison damage.
Dwarven Combat Training. You have proficiency with the battleaxe, handaxe, light hammer, and warhammer. As a Coral Dwarf you also have proficiency with tridents and heavy crossbows.
Tool Proficiency. You gain proficiency with the artisan's tools of your choice: smith's tools, brewer's supplies, or mason's tools.
Stonecunning. Whenever you make an Intelligence (History) check related to the origin of stonework, you are considered proficient in the History skill and add double your proficiency bonus to the check, instead of your normal proficiency bonus.
Sea Walker. You can walk along solid surfaces within liquid at your normal walking speed, and you can breathe air and water. Additionally you can act as if you have a swimming speed while underwater.
Emissary of the Reef. Aquatic creatures have an extraordinary affinity with your people. You can communicate simple ideas with beasts and elementals. They can understand the meaning of your words and Aquan texts you carve in stone, though you have no special ability to understand them in return.
Guardians of the Depths. Adapted to even the most extreme ocean depths, you have resistance to cold damage.
Like other dwarves, coral dwarves are typically stocky figures, though beyond this there are many differences. Many are thicker than their surface brethren. Most obvious, however, is their many patches of odd colouration, on their skin and in their hair. These patches can be of any dwarven skin tone normally present along with pastel of any colour slanted towards their natural tone. Their irises could be any of a wide range of colours.