Made it my lifegoal. Currently fighting minor issues of work/life balance to gain income security to dedicate significant time to it. Currently looking for dual

Made it my lifegoal. Currently fighting minor issues of work/life balance to gain income security to dedicate significant time to it. Currently looking for dual-layer (if sufficiently cheap, also dual-side) BD-R sealed with desiccant and buried in suitable bodies of water (temperature stability against temperature-swing-induced fatigue of the data layers; yet retaining relative ease of access). Predicted cost 15€/TB (incl. sales tax) @ low redundancy (save against non-deliberate attacks via conventional weaponry), roughly doubling for resilience against multiple isolated thermonuclear devices (even in pathological locations w.r.t. the archive) or tripling (45€/TB) for a current-arsenal worst-case WW3 not deliberately targeting the archive. All assuming mass-migration after 50 years.