Well, it has been a few years since I last played dwarf fortress or visited the forum and I have to say that the changes to the gave are
amazing. Last time I fired it up we still didn't have caves and the military management page didn't require a degree from MIT to make sense (I jest, but in all honesty I probably should have made an effort to understand it BEFORE I was under siege). Everything from the necromancers to the evil bioms to the caverns show an incredible improvement over previous versions of the game. I know that for those who have been updating constantly, changes seem incremental but when you go a few years without playing it feels like a new and better game altogether. Well done Dr. Toad.
Anyways, so, I accidently spawned a map with two sprawling continents (I never did take the time to understand how to engineer worlds according to custom parameters. The great thing about this map is that the continents at their most narrow point are separated by an area of ocean that can actually be encompassed within a 4x4 map. To make things better, one side is home to elves, humans, and dwarfs while the other includes all of the above in addition to goblins. My plan is to build a large bridge and inhabit it as an above-ground and below-water fortress. I am modeling the idea off of The Twins, the stronghold of House Frey from 'A Song of Fire and Ice'.
I would like to move the towers further out into the ocean itself, and I am wondering if anybody has ideas about how I can build a tower that extends down to the ocean floor. As I understand it, cave-ins destroy constructed walls, so constructing and then dropping huge pillars down wouldn't work. One idea I had was to cast them out of obsidian and then drop them into the ocean; which could offer other benefits, such as allowing me to engrave the walls and also scoring me major dwarf-ness points. That being said I would like to be able to accomplish it in a reasonable amount of time.
Also, will the goblins ever appear from the wrong side of the ocean, i.e. the area that isn't regarded as being accessible to them?
Edit:
Here are the worldgen parameters:
Created in DF v0.34.10.
[WORLD_GEN]
[TITLE:CREATE WORLD NOW = 4445554]
[SEED:iya68UQuK8AMuIoU4MAI]
[HISTORY_SEED:iW2yYgq4Ksek4suKoq8E]
[NAME_SEED:kCk4sIYoqaCkGQCQmaYq]
[CREATURE_SEED:es4wIwqI6c0S6iUusOwG]
[DIM:129:129]
[EMBARK_POINTS:1324]
[END_YEAR:550]
[BEAST_END_YEAR:550:-1]
[REVEAL_ALL_HISTORY:1]
[CULL_HISTORICAL_FIGURES:0]
[ELEVATION:1:400:1600:1600]
[RAINFALL:0:100:200:200]
[TEMPERATURE:25:75:200:200]
[DRAINAGE:0:100:200:200]
[VOLCANISM:0:100:200:200]
[SAVAGERY:0:100:200:200]
[ELEVATION_FREQUENCY:4:2:0:1:0:1]
[RAIN_FREQUENCY:1:1:1:1:1:1]
[DRAINAGE_FREQUENCY:1:1:1:1:1:1]
[TEMPERATURE_FREQUENCY:1:1:1:1:1:1]
[SAVAGERY_FREQUENCY:3:1:2:3:4:5]
[VOLCANISM_FREQUENCY:1:1:1:1:1:1]
[MINERAL_SCARCITY:500]
[MEGABEAST_CAP:36]
[SEMIMEGABEAST_CAP:74]
[TITAN_NUMBER:18]
[TITAN_ATTACK_TRIGGER:80:0:100000]
[DEMON_NUMBER:28]
[NIGHT_TROLL_NUMBER:14]
[BOGEYMAN_NUMBER:14]
[VAMPIRE_NUMBER:14]
[WEREBEAST_NUMBER:14]
[SECRET_NUMBER:28]
[REGIONAL_INTERACTION_NUMBER:28]
[DISTURBANCE_INTERACTION_NUMBER:28]
[EVIL_CLOUD_NUMBER:14]
[EVIL_RAIN_NUMBER:14]
[GOOD_SQ_COUNTS:6:63:0]
[EVIL_SQ_COUNTS:6:63:0]
[PEAK_NUMBER_MIN:3]
[PARTIAL_OCEAN_EDGE_MIN:0]
[COMPLETE_OCEAN_EDGE_MIN:4]
[VOLCANO_MIN:1]
[REGION_COUNTS:SWAMP:66:0:0]
[REGION_COUNTS:DESERT:66:0:0]
[REGION_COUNTS:FOREST:264:0:0]
[REGION_COUNTS:MOUNTAINS:528:0:0]
[REGION_COUNTS:OCEAN:528:0:0]
[REGION_COUNTS:GLACIER:16:0:0]
[REGION_COUNTS:TUNDRA:33:0:0]
[REGION_COUNTS:GRASSLAND:528:0:0]
[REGION_COUNTS:HILLS:528:0:0]
[EROSION_CYCLE_COUNT:250]
[RIVER_MINS:25:25]
[PERIODICALLY_ERODE_EXTREMES:1]
[OROGRAPHIC_PRECIPITATION:1]
[SUBREGION_MAX:2750]
[CAVERN_LAYER_COUNT:3]
[CAVERN_LAYER_OPENNESS_MIN:0]
[CAVERN_LAYER_OPENNESS_MAX:100]
[CAVERN_LAYER_PASSAGE_DENSITY_MIN:0]
[CAVERN_LAYER_PASSAGE_DENSITY_MAX:100]
[CAVERN_LAYER_WATER_MIN:0]
[CAVERN_LAYER_WATER_MAX:100]
[HAVE_BOTTOM_LAYER_1:1]
[HAVE_BOTTOM_LAYER_2:1]
[LEVELS_ABOVE_GROUND:15]
[LEVELS_ABOVE_LAYER_1:5]
[LEVELS_ABOVE_LAYER_2:1]
[LEVELS_ABOVE_LAYER_3:1]
[LEVELS_ABOVE_LAYER_4:1]
[LEVELS_ABOVE_LAYER_5:2]
[LEVELS_AT_BOTTOM:1]
[CAVE_MIN_SIZE:5]
[CAVE_MAX_SIZE:25]
[MOUNTAIN_CAVE_MIN:20]
[NON_MOUNTAIN_CAVE_MIN:30]
[ALL_CAVES_VISIBLE:0]
[SHOW_EMBARK_TUNNEL:2]
[TOTAL_CIV_NUMBER:80]
[TOTAL_CIV_POPULATION:15000]
[SITE_CAP:2000]
[PLAYABLE_CIVILIZATION_REQUIRED:1]
[ELEVATION_RANGES:8000:1056:528]
[RAIN_RANGES:528:1056:528]
[DRAINAGE_RANGES:528:1056:528]
[SAVAGERY_RANGES:0:2080:4160]
[VOLCANISM_RANGES:528:1056:528]