Place washed and sliced cucumbers in a large bowl. Cover with a layer of ice cubes and refrigerate for 4 hours. Drain completely.
Combine salt, vinegar, and water. Heat to boiling.
Pack the cucumbers into jars. Leave 1-inch headspace. Place dill, garlic, mustard seeds, and peppercorns into each jar.
Pour hot vinegar brine over cucumbers and spices in each jar, leaving ½ inch of headspace.
Cap and seal. Place in canner with 2 to 3 inches of hot water.
Pressure cook for 15 minutes on High. Once done, allow pressure to come down naturally before opening cooker.