I would love to know whom they are minding it from ?
Chain of custody. They have to be able to prove the 'stuff' they seized out at sea is the same cocaine as tested in the State lab is the same cocaine produced in the court case. Otherwise the accused could claim they were transporting talcum powder and someone must have switched it while the boat was unattended. Reasonable doubt and all that! I'm sure stranger things have happened in court!
Also I have a vague memory from decades ago of drugs been seized in Dublin airport and they were stored overnight in the nearby Santry Garda station. Or maybe it was a lorry full of drugs? Anyhow, someone broke in overnight and stole it back! People do weird things when drugs are involved...