The increase in population and its needs have worsened the issue of metal contamination of the environment, negatively impacting plants, animals, and human health. New Caledonia, a biodiversity hotspot, faces a significant source of metals from mining activity and erosion that affect unique ecosystems that require protection. In this study, we explore the potential of halophytes to remediate metals, with the aim of safeguarding seashores and lagoons. We examine the optimal growth and metal bioaccumulation conditions of two halophytic species, Sesuvium portulacastrum (L.) L. and Suaeda australis (R.Br.) Moq, which dominates the salt marshes of New Caledonian coasts. These species were subjected to two levels of metal concentration and two levels of irrigation frequency, which mimic the fluctuation in soil water content due to seasonal changes and tidal irregularities. The results showed that S. portulacastrum growth was enhanced when the irrigation frequency was lowered, while S. australis preferred constant soil moisture. S. australis accumulated more Ni, Co, and Cr than S. portulacastrum, especially in the roots. However, S. portulacastrum transported more metals in the aerial parts than S. australis. This work showed promising abilities of both species to accumulate metals and suggests further research to improve their metal phytoremediation potential in New Caledonian salt marshes.